grant connect,create table to test1;
conn cyts_cc/cyts_cc@orcl2000;
create table(
id int)
tablespace user;
ERROR 位于W?1 ?
ORA-01950: 表空?USERS'中无权限
conn cyts_cc/cyts_cc@orcl2000;
alter user test1 quota 1M on users;
create tab
(id int);
success
alter user test1 account lock;
conn test1/test1@orcl2000;
ERROR:
ORA-28000: the account is locked
1 Database Schema
a schema is a named collection of objects
b user is created and a corresponding schema is created
c user can be associated only with one schema
d username and schema are often userd interchangely.
2 Checklist for creating users
a idntfigy tablespaces in which the usr nedds to store objects
b decide on quotas for each tablespace
c assign a default tablespace and temporary tablespace.if you do not specify at the time of create user,system tablespace will be the defalut tablespace and temporary.it will affect the performance of the oralce.
d create user
e grant privileges and roles to user
desc dba_users;
select * from dba_users;
3 Creating a new user:
Database Authentiacation
set the initial password
create user aaron
identified by soccer
default tablespace data
temporary tablespace temp
guota 15m on data
password expire;
alter database default temporary tablespace temp;
4 Creating a new user operating System Authentication
os_authent_prefix initialllization parameter specifies the format of the username
defauts to ops$
create user arron
identified externally
default tablespace users
temporary tablespace temp
quota 15m on data
password expire;
conn /
show parameter os
os_authent_prefix string OPS$
create user ops$test3
identified externally
default tablespace us
temporary tablespace
quota 10m on users
thee test2 is an user of os ,which the oracle is installed.
5 Changing user quota on tablespace
alter user test3 quota 4m on users;
you cann't grant quota on temp and undotbs.
alter quota 0 on uers -- means that no new table space can be allocated and cannot change the exist object in the tablespaces
6 drop user
you cannot drop user who has connected to oracle
drop user (cascade)
7 Obtaining User information
information about uers can be obtained by qerying the data dictionary
dba_users
名称
-----------------------------
USERNAME
USER_ID
PASSWORD
ACCOUNT_STATUS
LOCK_DATE
EXPIRY_DATE
DEFAULT_TABLESPACE
TEMPORARY_TABLESPACE
CREATED
PROFILE
INITIAL_RSRC_CONSUMER_GROUP
EXTERNAL_NAME
dba_ts_quotas
名称
---------------
TABLESPACE_NAME
USERNAME
BYTES
MAX_BYTES
BLOCKS
MAX_BLOCKS
]]>
is
begin
dbms_output.put_line(systimestamp);
end;
a 使用execute 命o调用q程
set serveroutput on
exec out_time;
b 使用call 命o调用q程
set serveroutput on
call out_time();
2) 建立q程Q带有in参数 默认入参敎ͼ另外也可以用in 关键子显C的定义
create or replace procedure add_employee
(eno number,name varchar2,sal number,
job varchar default 'clerk',dno number)
is
e_integrity exception;
pragma exception_init(e_intgegrity,-2291);
begin
insert into emp(empno,ename,sal,job.deptno)
values(eno.name,sal,job,dno);
exception
when dup_val_on_index then
raise_application_error(-20000,'雇员号不能重?);
when e_integrity then
raise_application_error(-20001,'部门号不存在');
调用
exec add_employee(111,'clark',200,'manager',10);
3 建立q程Q带有out 参数
create or replcace procedure query_employee
(eno number,name out varchar2,salary out number)
is
begin
select ename,sal,into name,salary from emp where empno=eno;
exception
when no_data_found then
raise_application_error(-20000,'G该雇员不存在');
end;
调用
var name varchar2(10)
var salary number
exec query_employee(7788,:name,:salary);
print name,salary;
4 建立q程Q带有in out 参数
create or replace procedure compute
(num1,in out number,num2 in out number)
is
v1 number;
v2 number;
begin
v1:=num1/num2;
v2:=mod(num1,num2);
num1:=v1;
num2:=v2;
end;
调用
var n1 number
var n2 number
exec :n1:=100;
exec :n2:=30
exec compute(:n1,:n2)
print n1 n2
5) 为参C递变量和数据 位置传递，名称传递，l合传?br /> create or replace procedure add_dept
(dno number,dname varchar2 default null,loc varchar default null)
is
begin
insert into dept values(dno.dname,loc);
end;
-- 位置传?br /> exec add_dept(50,'sales','new york');
exec add_dept(60);
exec add_dept(70,'admin');
-- 名称传?br /> exec add_dept(50,loc=>'new york');
exec add_dept(60,dname=>'sales',loc=>'new york');
6) 昄当前用户的所有程序及其源代码
select text from user_source where name='add_dept';
7) 删除q程
drop procedure add_dept;
2 开发函?br /> 可以在sql语句和其他子q程中执行?br /> 1 建立函数Q不带Q何参?br /> create or replace function get_user
return varchar2
is
v_user varchar2(100);
begin
select username into v_user from user_users;
return v_user;
end;
--使用变量接收函数q回?br /> var v2 varchar2(100)
exec :v1:=get_user
print v1;
-- 在sql 语句中直接调用函?br /> select get_user from dual;
-- 使用dbms_output 调用函数
set serveroutput on
exec dbms_output.put_line('get_user');
2) 建立函数Q带有in 参数
create or replace function get_sal(name in varchar2)
reutnr number
as
v_sal emp.sal%type;
begin
select sal into v_sal from emp where upper(ename)=upper(name);
return v_sal;
exception
when no_data_found then
raise_application_error(-20000,'employee does not exist');
end;
3) 建立函数Q带有out 参数
create or replace function get_info
(name varchar2,title out varchar2)
return varchar2
as
deptname dept.dname%type;
begin
select a,job,b,dname into title,deptname from emp a,dept b
where a.deptno=b.deptno
and upper(a.ename)=uppder(name);
return deptname;
end;
var job varchar2(20)
var dname varchar2(20)
exec :dname:=get_info('scott',job);
print dname job
4) 带有 in out 参数
create or replace function result
(num1,number,num2 in out nu8mber)
return number
as
v_result number(6);
v_remainder number;
begin
v_result:=num1/num2;
v_remainder:=mod(num1,num2);
num2:=v_remainder;
retrun v_result;
exception
when zero_divide then
raise_application_error(-20000,'zero divied');
end;
5) 函数调用的限?br /> -- 在sql 语句中只能调用存储函?br /> -- 在sql 语句中只能调用带有输入参数in Q而不能有输出参数out 和in out 参数的函?br /> -- 在sql 语句中调用的函数的参数必L标准的sql 数据cdQ不能是pl/sql 所Ҏ的数据类?br /> -- 在sql 语句中调用的函数不能包含insertQupdate 和delete
6) 查看源代?br /> set pagesize 40
select text form user_source where name='result';
7) 删除函数
drop function result;
3 理子程?br /> 1) 列出当前用户的子E序
select object_name,created,status form user_objects
where object_type in ('procedure','function');
2)列出子程序源代码
select text from user_sorce where name='raise_salary'
3)cd子程序编译错?br /> -- show errors
--使用数据字典user_errors 定错误原因和位|?br /> select line||'/'||position as "line/col",text error
from user_errors where name='raise_salary';
4) 列出对象的依赖关p?br /> -- 使用 user_dependenciess 定直接依赖关系
select name,type from user_dependencies
where referenced_name='emp'
-- 使用 deptree ?ideptree 定依赖和见解依赖关p?br /> select nested_level,name,type from deptree;
5) 重新~译子程?br /> 当被应用对象的结构被修改以后Q就会将相关依赖对象转变为无效invalid Q需要重新编?br /> 1
alter table emp add remark varchar2(100);
2
select object_name,object_type from user_objects
where status='invalid'
3
alter procedure add_employee compile;
alter view dept10 compile;
alter function get_info compile;
]]>
The union operator returns results form both queries after eliminating duplications.\
select employee_id,job_id
from employees
uniion
select employ_id ,job_id
from job_history;
2 the all operator
The union all opertor reutrn result from both queries,including all duplications
3 interset
select ster_id,qty from sales where qty>20;
intersect
select ster_id,qty from sales where ster_id like '7%';
4 minus
select ster_id,qty from sales where qty>20
minus
select ster_id from sales where ster_id like '7%'
5 set operator guidelines
. teh expressions in the select list must match in number and data type;
. Parentheses can be used to alter the sequence of the execution
.The order by clause:
can appear only at the very end of the statement
will accept the column name,aliases from thee firest select statement ,or thee positional notation
.Duplicate row are atuomatically eliminated except in union all.
.Column names from the first query appear in the result
.The output is sorted in ascending order by default except in union all
6 matching the select statement
select department_id,to_number(null),location,hire_date
from employees
union
select department_id,location_id,to_date(null)
from departments;
select employee_id,job_id,salary
from employees
union
select employee_id,job_id,0
from job_history;
7 Controlling the order of the rows
select 'sing' as "my dream" ,3,a_dummy
from dual
union
select 'like''d like to teach',1
from dual
union
select 'the world to',2
from dual
order by 2;
]]>
create or replace package emp_package is
g_deptno number(3):=30;
procedure add_employee(eno number,name varchar2,salary number dno number default g_deptno);
procedure fire_empoyee(eno number);
function get_sal(eno number) return number;
end emp_package;
2) 建立包体
用于实现包规范所定义的过E和函数。在包体中也可以单独定义U有lgQ包括变量，帔RQ过E和函数{。但在包体中所定义的组件只能在包内使用Q而不能由其他子程序引用?br /> create or replace package body emp_package is
function validate_deptno(v_deptno number)
return boolean;
is
v_temp int;
begin
select 1 into v_temp from dept where deptno=v_deptno;
return true;
exception
when no_data_found then
return false;
end;
procedure add_employee(eno number,name varchar2,salary number,dno number default g_deptno)
is
begin
if validate_deptno(dno) then
insert into emp(empno,ename,sal,deptno)
values(eno,name,salary,dno);
esle
raise_application_error(-20011,'部门不存?);
end if;
exception
when dup_val_on_index then
raise_application_error(-20011,'该雇员已存在')
end;
procedure fire_employee(eno number) is
begin
select from emp where empno=eno;
if sql%notfound then
raise application_error(-20012,'');
end if;
end;
function get_sal(eno number) return number
is
v_sal emp.sal%type;
begin
select sal into v_sal from emp where empno=eno;
return v_sal;
exception
when no_data_found then
raise_application_error(-200012,'');
end;
end emp_package;
3) 调用包组?br /> Q－ 在同一个包内调用组?不需要加包名前缀Q直接调?br /> create or replace paclage body emp_package is
procedure add_employee(eno number,name varchar2,salary number,dno number default g_deptno)
is
begin
validate_deptno(dno) then
exception
end;
-- 调用包公用变?br /> exec emp_package.g_deptno:=20
-- 调用公用q程
exec emp_package.add_employee(111,'mary,2000');
-- 调用q程数据库包的公用组?br /> exec emp_paclage.add_employee@orasrv(1116,'scott',1200);
4) 查看包源代码
select text from user_source where name='emp_package' and type='package';
5) 删除?br /> drop packagee emp_package;
2 使用包重?br /> 指多个具有相同名字的子程序，在调用的时候用不同的参数传递?br /> 1) 建立包规?br /> 同名q程和函数必d有不同的输入参数Q但同名函数q回值的cd数据必须相同
create or replace package overload is
function get_sal(eno number) return number;
function get_sal(name varchar2) return number;
procedure fire_employee(eno number);
procedure fire_employee(name varchar2);
2) 建立包体
。。?br />3) 使用包构造过E?br /> 初始化全局变量
1 建立包规?br /> create or replace packiage emp_package
is
minsal number(6,2);
maxsal number(6,2);
procedure upd_sal(eno number,salary number);
procedure upd_sal(name varhcar2,salary number);
end;-- 定义了两全局变量和三个公用过E?br /> 2 建立包体
create or replace package body emp_package is
procedure add_employee(cno number,name varchar2,salary number,dno number)
is
begin
if salary between minsal and maxsal then
insert into emp(empno,ename,sal,deptno)
........
-- 构造过E，位于子程序尾部，已begin 开始已end l束
begin
select min(sal),max(sal) into minsal,maxsal from emp;
end;
end;
3 调用包公用组?br /> 在同一ơ会话中W一ơ调用包的公用组建时Q会自动执行其它构造函敎ͼ而将来调用其他组建时则不会再调用其构造过E?br />4 使用U度U别
1 安包规?br /> create or replcace package purity is
minsal number(6,2);
maxsal number(6,2);
function max_sal return number;
function min_sal return number;
pragma restrict_references(max_sal,wnps);--wnps 不能修改包的变量Q不能给包的变量赋| --wnds 不能执行dml
pragma restrict_references(min_sal,wnps);--rnps 用于限制函数不能d包变?br /> end;
]]>
预定义分c，非预定义分类Q自定义例外?br />2 处理预定义例?br /> 1) 常用预定义例?br /> a access_into_null;
create type emp_type as object
(name varchar2(2),sal number(6,2));
declare
emp emp_type;
begin
emp.name:='scott';
exception
when access_into_null then
dbms_output.put_line('首先初始化对象emp');
b case_not_found
undef no
declare
v_val emp.sal%type;
begin
select sal into v_sal from emp where empno=&no;
case
when v_sal<1000 then
update emp set sal=sal+100 where empno=&no;
when v_sal<2000 then
update emp set sal=sal+150 where empno=&no;
when v_sal<3000 then
update emp set sal=sal+200 where empno=&no;
end case;
exception
when case_not_found then
dbms_output.put_line();
end;
c collection is null
在给集合元素Q嵌套表或arraycdQ赋值前Q必首先初始化集合元素
declare type ename_table_type is table of emp.eanme%type;
ename_table ename_table_type;
begin
select e_name into ename_talbe(2) from emp where empno=$no;
exception
when collection_is_null then
dbms_output.put_lilne('必须使用构造方法初始化集合元素');
end;
d currsor_already_open
reopen curosr 如果用户已经使用了open 命o打开了显C游标，或执行for循环(隐式的打开游标)
delcare
cursor emp_surosr is select ename,sal,from emp;
begin
open emp_curosr;
for emp_record in emp_cursor loop
dbms_output.put_line(emp_record.eanme);
end loop;
exception
when cursor_already_open then
dbms_output.put_line("游标已经打开");
end;
e dup_val_on_index
begin
exception
when dup_val_on_index then
dbms_output.put_line("列上不能出现重复?);
end;
d invalid_curosr
delcare
curosr emp_cursor is select ename,sla from emp;
emp_record emp_crusor%rowtype;
begin
fetch emp_cursor into emp_record;
close emp_crusro;
exception
dbms_output.put_line("游标没有打开");
end;
f invalid_number can not convert char to nmuber successfully
begin
update mep set sal=sal+1oo;
exception
when invalid_number then
g no_data_found when select into is executed ,no row is returned
declare
v_sal emp.sal%type;
begin
select sal into v_cal form emp where lower(ename)=lower('&name');
exception
when no_data_found then
dbms_output.put_line('没有q回l果');
end;
h too_many_row ora -01422 there are too many are return when "select into" is executed
i zero_divide ora-01476
g subscript_beyond_count ora-065533
declare
type emp_array_type is varray(20) of varchar2(10);
emp_array emp_array_type;
begin
emp_array:=emp_array_type('scott','mary');
dbms_output.put_line('emp_array(3)');
exception
when subscript_beyone_count then
dbms_out.put_line('出下标范围');
end;
k subscript_outside_limit
emp_array(-1);
l value_error the length of variable cannot contain the actual value;
declare
begin
end;
3 处理非预定义例外
delcare
e_integrity exception;
pragma exception_init(e_integrity,-2291);
begin
update emp set deptno=dno where empno=&no;
exception
when a_integrity then
end;
4 处理自定义例?br /> 与oracle 错误没有M联系Qؓ业务逻辑所定义的例?br /> delcare
e_no_employee exception;
begin
update emp set deptno=&dno where empno=&eno;
if sql%notfound then
raise e_no_employee;
end if;
exception
when e_no_emplyee then
dbms_output.put_line('该雇员不存在');
5 使用错误例外函数
使用例外函数可以取得错误号以及相关的错误消息Qsqlcode 用于取得oracle 的错误号Q而sqlerrm
则用于取得与之相关的错误信息?br /> 1 sqlcode ?sqlerrm
Z在pl/sql 应用E序中处理其他ؓ预料的到的oracle 错误Q用户可以在例外处理部分?br />when others 自句后，引用两个函数
declare
v_ename emp.ename%type;
begin
select ename into v_ename form emp where sal='&v_sal';
exception
when no_data_found then
when others then
dbms_output.put_line(sqlcode);
dbms_output.put_line(sqlerrm);
end;
2 raise_aaplicaition_error
只能在子E序中用（q程Q函敎ͼ包，触发器）
raise_application_error(error_number,message,[true|false]);
error_number 错误P在－20000刎ͼ20999 之间
message 指定错误消息Q不能超q?048
if v_comm is null then
raise_application_error(-20001,'该雇员无补助');
end if;
]]>
to make complex query easy
to provide data independence
to provide defferent view of the same data
2 Creating a View
1)create [or replace] [force|noforce] view view
as subquery
force : create view wether the referenced object existed or not
desc view_name;
2)create a view by using column aliases in the subquery
create view salv50
as select employee_idIO_NUMBER,last_name NAME,slaary*12 ANN_SALARY
from employees
where department_id=50;
3 Modigy a View
1) Modigy the emplvu80 view by using create or replace view clause.Add an alias for each column name;
create or replace view empvu80
(id_number,name,sal,department_id)
as select employee_id,first_name||" "||last_name,salary.department_id
from employees
where department_id=80;
column aliases in the create view clause are listed in the same order as the columns in the subquery
note : alter view_name is not a valid command.
4 Create a Complex View
Create a complex view that contains group functions to display values from two tables
create view dept_sum_vu
(name,minsal,maxsal,avgsal)
as
select d.department_name,min(e.salary),max(e.salary),avg(e.salary)
from employees e,departments d
where e.department_id=d.department_id
group by d.department_name;
5 Rules for performs DML operaton on a view
1) You can perform DML operation on simple views
2) You can not romove a row if the view contains the following:
--group functions
--a group by clause
--the distinct keyword
-- rownum keyword
-- column defined by expressions
6 Using the with check option Clause
1) you can ensure that dml operatons performed on the view stay within the domain of the view by using the with check option clause.
create view test1
as
select * from emp where qty>10;
with check option;
update testview1 set qty=10
where ster_id=6830;
--when you doing the following update operation
update testview1 set qty=5 where id=10;
-- an error will report
--you violate the where clause
2)Any attempt to change the department number for any row in the view fails because it violates the with check option constraint
create or replace view empvu20
as
select * where department_id=20
with check option constriant empvu20_ck;
7 Denying DML Operations
1 You can ensure that no dml operations occur by adding the with read only option to your view definition.
2)Any attempt to a DML on any row in the view resuls in an oralce server error.
8 remove veiw
drop view_name
9 inline view
1) an inline view is a subquery with an alias that you can use within a sql statement.
2) a named subquery in the from clause of the main query is an exqmple of an inline view
3) an inline view is not a schema object.
10 Top-N Analysis
1)Top_N querise ask for the n largest or smallest values of a column.
2)Both largest values and smallest values sets considered Top-N queries
select * from (select ster_id,qty from sales);
example
To display the top three earner names and salaries from the employees
select rownum as rank,last_name,salary
from (select last_anme,slary from employee
order by slary desc)
where rownum<=3;
]]>
2) Constrains the deletion of a table if there are dependencies
2 Constrain Guidelines
1) Name a constraint or the oracle generate a name by the sys_cn format
2) Create a constraint either
--At the same time as the table is created.or
--After the table has been created
3)Define a constraint at the column or table level
4)view constraint in the data dictionary
3 Crete a constraint
create table test2
(id int not null,-- column level
lname varchar(20),
fname varchar(20),
constraint uk_test2_1 unique(lname,fname))--table level
4 The not null Constraint
create table employees(
employee_id number(6),
last_name varchar2(25) not null --system named
hire_date DATE
constraint emp_hire_date not null --User named
5Foreign key
create table test3
(rid int,
name varchar(30),
constraint fk_test3_1 foreign key(rid) reference test2(id));
froeign key constraint keywords
foreign key :Define the column in thee child table at the table constrain level.
references :Identifies the table and column in the parent table.
on delete cascade: Delete the dependent rows in the child table when a row in the parent table is deleted
on delete set null:Convert the dependent foreign key values to null when a row in the
parent table is deleted.
--parent table referenced table
--child table refernce other table
6 The check Constraint
Define a condition that each row must be satisfy
alter table test3
add constrain ch_test3 check(name like 's%')
7 Dropping a Constraint
1) Remove the manager constraint form the employee table
alter table test3
drop constriant test3_manager_fk
2) Remove the primary key constraint on the departments table and drop the associated
foreign key constraint on the employees.department_id column
alter table departments
drop primary key cascade
8 Disabling and enable Constraints
1)Execute the disable clause of the alter table statment to deactive an integrity constraint
2)Apply the cascade option to disable dependent integrity constrints
alter table employees
disable constraint emp_emp_id_pl cascade
3) enabling Constraints
.Active an integrity constraint currently disabled in the table definition by using the enable clause.
alter table employees
enable constraint emp_emp_id_pk;
a unique or a primary index is automatically created if you enable a unique key or a primary key constraint
8 View Constraints
select constraint_name,constriant_type,serch_condition
from user_constraints
where table_name='employees'
9 view the columns associated with constraints
select constraint_name,column_name
from user_cons_columns
where table_name='employees'
]]>
type ename_table_type is table of emp.ename%type
index by binary_integer;
ename_table ename_table_type;
begin
select ename into ename_table(-1) from emp
where empno=&no;
dbms_output.put_line('雇员名：'||ename_table(-1));
end;
set serveroutput no
declare
type area_table_type is table of number
index by varchar2(10);
rea_table area_table_type;
begin
area_table('beijing'):=1;
area_table('shanghai'):=2;
area_table('guangzhou'):=3;
dbms_output.put_line(area_table.first);
dbms_output.put_line(area_table.last);
end;
2) 嵌套?br /> 索引表类型不能作为篏得数据类型用，但是嵌套表可以作cȝ数据cd使用?br />当用嵌套表元素Ӟ必须先用其构造方法初始化其嵌套表Q?br /> a 在pl/sql 块中使用嵌套?br /> declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
ename_table:=eanme_table_type('2','2','3');
select ename into ename table(2) from emp where empno=&no;
dbms_ouput.put_line(ename_table(2));
end;
b 在表中用嵌套表
create type phone_type is table of varchar2(20);
create table employee(
id number (4),name varchar2(10),sal number(6,2),
phone phone_type
)nested table phone store as phone_table;
-- 为嵌套表插入数据
insert into employee values(2,'scott',200,phone_type('2222','333333'));
Q－索嵌套表累得数据
set serveroutput on
declare
phone_table phone_type;
begin
select phone into phone_table
from employee where id=1;
for i in 1..phone_table.count loop
dbms_output.put_line(phone_table(i));
end loop;
end;
-- 更新嵌套表列的数?br /> delcare
phone_table phone_type:=('44444','555555');
begin
update employee set phone=phone_table
where id=1;
end;
3) 变长数组
在用varray 时必L定最大个敎ͼ和数据类?在用其元素时必进行初始化
type ename_table_type is varray(20) of emp.ename%type;
ename_table ename_table_type:=ename_table_type('1','2');
-- 在快中用varray
declare
type ename_table_type is varray(20) of emp.enameQtypeQ?br /> ename_table ename_table_type:=ename_table_type('mary');
begin
select ename into ename_table(1) form emp
where empno=&no;
end;
--在表列中使用varray
create type phone type is varray(20) of varchar2(20);
create table employee(
id number(4),name varchar2(10),
sal number(6,2),phone phone_type);
3)记录?br /> 记录表结合了记录和集合的优点
declare
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * from into emp_table(1) from emp
where empno=&no;
dbms_output.put_line(emp_table(1).ename);
end;
4)多维集合
1 多varray
declare
--define 一l集?br /> type al_array_type is varray(10) of int;
--定义二维集合
type nal_varray_type is varray(10) of a1_varray_type;
--初始化二l集?br /> nvl nal_varray_type:=nal_varray_type(
a1_varray_type(1,2),
a1_varray_type(2,3)
)
beign
for i in 1..nal_varray_type.count loop
for j in 1..a1_array_type.count loop
dbms_out.putline(nvl(i)(j));
end loop;
end loop;
end;
2 使用多嵌套?br /> table a1_table_type is table of int;
table nvl_table_type is table of a1_table_type;
nvl nvl_table_type:=nvl_table_type(
a1_table_type(1,2),
a1_table_type(2,3)
);
2 集合Ҏ
1) exist
if ename_table.exists(1) then
ename_table(1):='scott';
2) count q回当前集合变量中的元素M?br /> ename_table.count
3) limit q回集合元素的最大个敊W?只有varray ?br /> 4)first and last
ename_table.first
ename_table.last
5) prior 和next
ename_table.prior(5); Q－q回元素5的前一?br /> ename_table.next(5); -- 后一?br /> 6) extend
使用于varray ?嵌套表?br /> extend add a null value
extend (n) add n null value
extend (n,i)add n i value
declare
type ename_table_type is varray(20) of varchar2(20);
ename_table ename_table_type;
begin
ename_table:=ename_table_type('mary');
ename_table.extend(5,1);
dbms_output.put_line(ename_table.count);
end;
7) trim
trim remove one element from the tail of the collection.
trim(n) remove n element from the tail of the colleciton.
8)delete
delete: delete all the elements
delete(n) :delete the nth elements
delete(m,n): delete the elements from m to n
3 集合赋?br /> 1)一个集合的数据赋值给另一个集?clear the destination collectins and set the original collection
delcare
type name_varray_type is varray(4) of varchar2(10);
name_array1 name_varray_type;
name_array2 name_varray_type;
begin
name_array1:=name_varray_type('scott','smith');
name_array2:=name_array_type('a','b','c');
name_array1:=name_array2;
end;
type name_array1_type is varray(4) of varchar2(10);
type name_array2_type is varray(4) of varchar2(10);
name_array1 name_array1_type;
name_array2 name_array2_type;
h相同的数据类型，单具有不同的集合cd不能构赋?br /> 2) l集合赋城null ?br /> 可以使用delete ?trim
也可以?I集合赋l目表集?br /> type name_varray_type is varray(4) of varchar2(10);
name_array name_varray_type;
name_empty name_varray_type;
name_array:=name_varray_type('1','2');
name_array:=name_empty;
3) 使用集合操作赋和比较集合都是10g 的内容，p176 先略q?br />4 扚wl定
执行单词sql 操作能传递所有集合元素的数据?br /> 1 forall 语句
用于insert update 和delete操作。在oracle9i 中forall 语句必须hq箋的元?br /> 1) using forall on insert
declare
type id_table_type is table of number(6)
index by binary_integer;
type name_table_type is table of varchar2(2)
index by binary integer;
id_table id_table_type;
name_table name_table_type;
begin
for i in 1..10 loop
id_table(i):=i;
name_table(i):='Name'||to_char(i);
end loop;
forall i in 1..id_table.count
insert into demo values(id_table(i),name_table(i));
end;
2)using forall on using update
forall i in 1..id_table.count
upate demo set name:=name_table(i)
where id:=id_table(i);
3)using forall on using delete
forall i in 1..id_table.count
delete from demo where id:=id_table(i);
4) using forall on part of the collection
for i in1..10 loop
id_table(i):=i;
name_table(i):="name"||to_char(i);
end loop;
forall i in 8..10 l
insert into demo values(id_table(i),name_table(i));
2 bulk collect
is fit for select into ,fetch into and dml clause
1) using bulk collect
declares
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * bulk collect into emp_table
from emp where deptno=&no;
for i in 1..emp_tablee.count loop
dbms_output.put_line(emp_table(i).ename);
end loop;
2) 在dml 的返回字句用bulk collect 字句
declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
deletee from emp where deptno=&no
returning ename bulk_collect into ename_table;
for i in 1..ename_table.count loop
dbms_output.put(ename_table(i));
end loop;
end;
end;
end;
]]>
1 使用execute immediate 处理ddl 操作
create or replacee procedure drop_table(table_name varchar2)
is
sql_statement varchar2(100);
begin
sql_statement:='drop table'||table_name;
execute immediate sql_statement;
调用
exec drop_table('worker');
end;
2) 使用 execute immediate 处理dcl 操作
create or replace procedure grant_sys_priv
(priv varchar2,username varchar2)
is
begin
sql_stat:='gruant'||priv||'to'||username;
execute immediate sql_stat;
end;
exec grant_sys_priv('create session','scott');
3 使用execute immediate 处理dml 操作
1) 处理无占位符和returning 子句的dml 语句
delcare
sql_stat varchar2(100);
begin
sql_stat:='update emp set sal=sal*1.1 where deptno=44';
execute immediate sql_stat;
end;
2) 处理包含占位W的dml语句
delare
sql_stat varchar2(100);
begin
sql_stat:='update emp set sql=sql*(1+:percent/100)'
||'where deptno=:dno';
execute immediate sql_stat using &1,&2;
end;
3) 处理包含returning 子句的dml语句
declare
salary number(6,2);
sql_stat varchar2(200);
begin
sql_stat:='update emp set sal=sal*(1:percent/100)'
||'where empno=:eno returning sal into :salary';
execute immediate sql_stat using &1,&2;
returning into salary;
end;
输入1的?15
输入2的?2222
新工资；2223
4) 使用execute immediate 处理单行查询
declare
sql_stat varcchar2(100);
emp_record emp%rowtype;
begin
sql_stat:='select * from emp where empno=:eno';
execute immediate sql_stat into emp_record using &1;
end;
3 处理多行查询语句
declare
type empcurtyp is ref cursor;
emp_cv empcurtyp;
emp record emp%rowtype;
sql_stat varchar2(100);
begin
sql_stat:='select * from em where deptno=:dno';
open emp_cv for sql_stat using &dno;
loop
fetch emp_cu into emp_record;
exit when emp_cv%notfound;
end loop;
close emp_cv;
end;
4 在动态sql 中用bulk语句
1) ?execute immediate 语句中用动态bulk 语句
declare
type ename_table_type is table of emp.ename%type
index by binary_integer;
type sal_table_type is table of emp.sal%type
index by binary_integer;
ename_table ename_table_type;
sa_table sal_table_type;
sal_stat varchar2(100);
begin
sql_stat:='update emp set sal=sal*(1+:percent/100)'
|| 'where deptno=:dno'
||'returning ename,sal into :name,:salary';
execut immediate sql_stat using &percent,&dno
returning bulk collect into ename_table,sal_table;
for i in 1..ename_table.count loop
....
end loop;
end;
2) 使用bulk 子句处理多行查询
sql_stat:='select ename from emp where deptno=:dno';
execute immediate sql_stat bulk collect into ename_table using &dno;
3) 在fetch 语句中用bulk 子句
declare
type empcurtyp is ref cursor;
emp_cv empcurtyp;
type ename_table_type is table of emp.ename%type;
index by binary_integer;
ename_table ename_table_type;
sql_stat varchar2(100);
begin
sql_stat:='select ename from emp where job:=title';
open emp_cv for sql_stat using '&job';
fetch emp_cv bulk collect into ename_table;
4) 在forall 语句中用bulk 子句
declare
type ename_table_type is table of emp.ename%type;
type sla_table_type is table of emp.sal%type;
ename_table ename_table_type;
sal_table sal_table_type;
sql_stat varchar2(100);
begin
ename_table:=ename_table_type('scott','smith','clark');
sql_stat:='update emp set sal=sal*1.1 where ename=:1'
||'returning sal into :2';
forall i in 1..ename_table.count
execite immediate sql_stat using ename_table(i)
returning bulk collect into sal_table;
end;
]]>
.the result of the subquery is used by the main query.
2 pairwise comarison subquery
select * from employee
where (manager_id,department_id) in
(select manager_id,department_id
from employees
where employee_id in (178,174))
and employee_id not in (178,174);
nonpairwise comparison subquery
select employee_id,manager_id,department_id
from employee
where manager_id in
(select manager_id
from employees
where employee id in (174,141))
and department_id in
(select department_id
from employees
where employee_id in (174,141))
and employ_id not in (174,141);
)
3 using a subquery in the from clause
select a.last_name,a,salary,b.slaavg
from employees a ,(select department_id,
avg(salary) salavg
from employees
group by department_id) b
where a.department_id=b.department_id
and a.salary>b.salavg;
4 scalar subquery expressions
. a scalar subquery expression is a subquery that return exactly on column value from one row
. in oracle8i scalar subqueries can be used in condition and expression part and all clause.
1) sclaar subqueries in casse expression
select employee_id ,last_name,
(case
when department_id=
(select department_id from departments
where location_id=1800)
then 'canada'
else 'usa'
end) location
from employees
2)scalar subqueries in order by clasue
select employee_id,last_name
from employees e
order by (select department_name
from departments d
where e.department_id=d.department);
4 correlated subqueries
the wubquery references a column form a table in the parment query
select column1,solumn2....
from table1 outer
where column1 operator
(select column1,column2
from table2
where expr1=out.expr2);
e.g 1
select last_name,salary,department_id
from employees outer
where salary>
(select avg(salary)
from employees
where department_id=
outer.department_id);
)
e.g 2
display details of those employees who have switched jobs at lease twice
select e.employee_id,last_name,e.job_id
from employees e
where 2<=(select count(*)
from job_history
where employee_id=e.employee_id);
6 using the exists operator
. the exists operator tests for existencee of rows in the results set of the subquery
. if a subquery row value id found:
the search does not continue in the inner query
the condition is flagged true
.if a subquery row value is not fount
the condition is flagged fasle
the search continues in the inner query
e.g
find employees who have at least one person reporting to them
select employee_id,last_name,job_id,department_id
from employees outer
where exists (select count(*)
from employees
where manager_id=outer.employee_id);
not exist.
7 corelated update
use a correlated subquery to update rows in on table based on rows from another table
e.g
--denormalize the employees table by adding a column to store the department name
alter table employees
add(department_name varchar2(14));
--populate the table by using a correlated update
update employees e
set department_name=
(select department_name
from departments d
where e.departmentid=d.department);
8 correlated delete
delete test1 t1
where ster_id in(select ster_id form sales t2 where t.ster_id=t2.ster_id);
9 using the with clause ,you can use the same query block in a a select statement when it cocurs more than once within a complex query
the with clause retrieves the results of a query block and stores it in the user's the user's templary tablespace
the with clause improves performance.
e.g
with
dept_costs as(
select d.department_name,sum(e.salary) as dept_total
from employee e,departments d
where e,department_id=d.department_id
group by d.department_name),
avg_cost as(
select sum(dept_total)/count(*) as dept_avg
from dept_cost)
select *
from dept_costs
where dept_total>(select dept_avg
from afb_cost)
order by department_name;
]]>
select [level],colun,expr......
from table
[where condition(s)]
[start with condition(s)]
[connect by prior condition(s)]
where condition
exprcompparison_operator expr
2 Starting Point
.Specifies the condition that must be met
.Accepts any valid condition
3 Waling the Tree
connect by prior column1=column2
walk from the top donw ,using the employees table
top donw
column1=parentkey
column2=childkey
bottom up
column1=child key
column2=parent key
select level,last_name
from employees
start with last_name='king'
connect by prior employee_id=manager_id;
]]>
in oracle 9.2.0,spfile is stored in the directory of ora92\datatase\spfile<sid>.ora.
2)init parameter file(pfile)--init<sid>.ora (early version) is a text file.it is stored in admin\<sid>\pfile.
2
Entries are specific to the instance being accessed;
there are two kinds of parameters:
explicit: having an entry in the file
implicit: no entry within the file,but assuming the oracle default values;
Multiple files can be used for a single datasbase to optimize performance in different situation.
static parameter file,pfile (init.ora)
persistent parameter file,spfile(spfile<sid>.ora);
3 order being used
first spfile<sid> then int<sid>.ora
select name,value from v$system_parameter
4 spfile spfilesid.ora
1)Binary file with the abiility to make changes persistent across shutdown and startup
2)Maintained by oracle server
3)Record parameter value change made with the alter system command
4)Can specify wether the change being made is tempory or persistent
5)value can be delete or reset to allow an instance to revert to the default value;
e.g
alter system set timed_statistics=false scope=memory;
alter system set timed_statistics=false scope=spfile;
startup force-- restart oracle
select name,value from v$system_parameter where name like 'time%';
alter system set timed_statistics=false scope=both;
6) not all entries can be modified.to see more ,you can lool up v$system_parameter.in this table the isses_modifiable and issys_modifiable will tell which one can be modified in session,and which one can be modified in sys, and which one cann't be modified.
e.g
select name,isses_modifiable from v$system_parameter where isses_modifiable='true';
alter session set timed_statistics=false;
e.g
select name,issys_modifiable from v$system_parameter where issys_modifiable<>'false';
.issys_modifiable may have two values immediate or deffered.
immediate means alter this entry will take effect on the current session ,while derrered will take effect on a new session.
5 pfile initsid.ora
.the pfile is a text file than can be modigied with an operation system editor.
.modifications to the file are made manually.
.changes to the file take effect on the next startup
6 Creating an spfile
spfile can be created from initsid.ora file using thee create spfile command,whick can be executed before or after instance startup.
create spfile from pfile. -- you must shutdown the instance befofe or you can use the fellow statement:
create spfile='d:\oracle\oracle\ora92\database\spfile.ora' from pfile;
yo caan backup the
7 Oracle Managed files(OMF)
1) OMF are created and deleted by the oracle server as directed by sql commands
2) OMF are established by parameters:
DB_CREATE_DEST: set to give the default location for data files
DB__CREATE_OMLINE_LOG_DEST_N: set to gieve the default locations for online redo logs and control files,up to a mazimum of 5 locations.
e.g 1
show parameter db_create
e.g 2
create tablespace test1;--report error,Do not konw where create the data file
alter system set db_create_file_dest='d:\oracle\oradb';
create tablespace test1; -- is ok;
e.g 3
alter database add logilfe group 6;
-- if you do not specify the db_create_online_log_dest_N ,the log file will create at --the location which is specified by the db_create_file_dest.
e.g 4
drop table test1; -- oracle alse remove it's physicial file;
alter database drop logfile group 6-- also romove the physical file.
e.g 5
create tablespace test1
datafile 'd:\oracle\oradb\test1.dbf' size 2m;
drop tablespace test1 -- if you create tablespace or others object in this way ,you --will cann't remove the physical file.
drop table test1 including comtents and datafiles;
8 Starting up a database mount
startup nomomount :instance started for this instance;create db.create controlfule
1) create alert_sid.log startup log which is stored in <oracle_home>\admin\<sid>\bdump
2) start instance include allocating memory and start bpprocess
select * from v$instance;
select * from v$bgprocess;
select * from V$sga;
alter database mount;
open control files for the instance;
select* from v$database;
select* from v$tablespace;
select* from datafile;
select* from log;
alter database open;
all files opened as describled by the control file for this instance;
9 start up
start pfile=...\initsid.ora; (alter session set nls_language=american)
alter database open read only; you can not change database to read only after the database has been created.
startup database restrict;
alter system enable restricted session;-- only people with restricted privilege can --access the database;
alter restricted session to kkk;
alter disable restricted session
10 opening a database in read only mode
a databse can be opened as read only database alter database open read only;
a read-only database can be used to :
execute queries
execute disk sorts using locally managed
take data files offline and online ,not tableespaces
perform recovery of offline data files and tablespace;
11Shutting down teh database
normal: wait until current sessions end,wait until current trasactions end ,force a checkpoint and close files.
tansactional:wail until current transaction end.force a checkpoint and close files
immediate :force a checkpoint and close the files
abort : do nothing ,just close the files. when startup ,need recovery.
12 Managing an instance by monitoring Diagnostic Files
Diagnostic files contain information about significant events encounted while the instance is operational.
.user to resolve problem or to better manager the database.
.server types of dignostic files exist:
alertsid.log --which location is specified by the background_dump_dest --entry in the initsid.ora.tje default value is --<ora_home>\admin\sid\bdump
background trace files -- the same as above;
user_tace files
13 alert log file
the alertsid.log file recored the command and result of major event while the database is operational.
.it is userd for day-to-day operational information or dignosing database errors
.ench entry has a time stamp associated with it.
.the dba manager the alertsid.log file.
.its location is defined by background_dump_dest.
14 enabling or disabling user tracing
. sessin level using the alter session
alter session set sql_trace=true;
session level by execcuting dbms
]]>
1)a profile is a named set of password and resource limits
2)Profiles are assigned to user by the create user or alter user command
3)can be enable or disable
4)can relate to the default profile.
2 Password Management
Password history,account locking,password expiration and aging ,password verificcation.
3Enabling Password Management
1)set up passwordd management by using profiles and assign them to users
2)lock unlock and expire accounts usign the create user or alter user
3)alwarys enforcing
e.g
create user test identified by test;
alter user test account lock;
alter user test account unlock;
alteer user test password expire;
4 Passowrd Account locking
FAIKED_LOGIN_ATTEMPS: number of failed login attemts before lockout of the account
PASSWORD_LOCK_TIME : number of days the account is locked after the specified number of failed login attemps
e.g
create profile profile1 limit
password_lock_time 1/1440 -- one muinuts
failed_login_attempts 3;
alter user test
profile profile1;
alter profile profile1 limit
passowrd_lock_time 1/24 --one hour
5 passowrd expiration and aging
passwowd_life_time lifetime of the passowrd in days after which the password expires(有效?
password_grace_time grace period in days for changing the password after the first successful login afteer the password has expired(锁定?
e.g
alter profile profile1 limit
password_life_time 2
password_grace_time 3;
6 password history
password_reuse_time:number of days before a passowrd and be resued
password _reuse_max:maxum number of times password can bee reused
e.g
alter profile profile1 limit
password_reuse_time 10
password_reuse_max 3;
7passowrd Verification(study latter)
8drop a profile
drop profile profile1 (cascade);
the user will use the default profile.it will take effect on the new session.
9 Resource Management
Resource mangement limits can be enforced at the session level,the call level or both
limits can be defined by profiles using the create profile command
enable resource limints with the
.resource_limit initialization parameter
alter system command
e.g
alter system set resource_limit=true;
10 setting a Resdource limits at session level
cup_per_session : total cpu time measured in hundredths of seconds (癑ֈ之一U?
sessions_per_user: number of coucurrent sessions allowed for each username
connect_time:elapsed connect time measured in minutes
idle_time :periods of inactive time measured in minutes
logical_reads_per_session: number of data blocks
private_sga :measure in reads
e.g
alter profile profile1 limit
cpu_per_session 100000
connect_time 60
idle_time 5;
alter user test profile profile1
11 Setting Resource limits at call level
e.g
alter profile profile1
cpu_per_call 1000 -- cup time per call in
logical_reads_per_call --number of data balock that can be read per call
create profile develper_prof limit
session_per_user2
cpu_per_session 10000
idle_time 60
connect_time 480
12 Managing Resources using database resource manager
1)Provides the oracle server with more control over resorce management decisions
2)elements of database resorcee manager
resource consumer group
resourcee plan
resource allocation method
resource plan directives
3)dbms_resource_manager package is uerd to create and maintain elements
4)requires administer_resource_manager privilege
desc dbms_resoource_manager
13 0btaining password and resource limits informaiton
information about password and resource limits can be obtained by querying the data dictonary
dba_users
select * from users;
dba_profiles
select * from dba_profiles where profile='PROFILE1'
]]>
2) multitable insert statements can be used in data warehousing systems to transfer data from one or more operational sources to source to a set of target table.
3) they providde significant performance improvement over
single dml versuls multiple insert...select statement
single dml versus a proceedduree to do mutiple inserts using if ,,, then syntax.
2
unconditional insert
insert all
into sal_history values (EMPID,HIREDATE,SAL)
into mgr_history values (EMPID,MGR,SAL)
select employee_id EMPID,hire_date JIREDATE,
salary SAL,manager_id MGR
from employees
where employee_id>200;
3 Conditional insert all
insert all
when sal>1000 then
into sal_history values(empid,hiredate,sal)
when mgr>200 then
into mgr_history values(empid,mgr,sal)
select emp_id empid,hire_date hiredate,salary sal,manager_id mgr,
from employees
where employee_id>200;
4 Conditional first insert
insert first
when sal >25000 then
into special_sal values(deptid,sal)
when hiredate like ('%00%') then
into hiredate_history_00 values(deptid,hiredate)
when hiredate like ('%99%') then
insert hiredate_history_99 values(ddeptid,hiredate)
else
into hiredate_history values(deptid,hiredate)
select ddepartmeent_id deptid,sum(salary) sal,
max(hire_date) hiredate
from employees
group by department_id;
5 Pivoting insert
insert all
into sales_info values (employee_id,week_id,sales_mon)
into sales_info values (employee_id,week_id,sales_tue)
into sales_info values (employee_id,week_id,sales_wed)
into sales_info values (employee_id,week_id,sales_thur)
into sales_info values (employee_id,week_id,sales_fri)
select employee_id,weekid,sales_mon,sales_tue,sales_wed,sales_thur,sales_fri
from sales_source_data;
6 create index with create table statement
create table new_emp
(employee_id number(6)
primary key using index
(create index emp_id_idx on new_emp(employee_id)),
first_name varchar2(20),
last_name varchar2(25)
)
]]>
1) Database security:
--System security
--Data security
2)System privileges:Caining access to the database
3)Object privileges:manipulationg thee content of the database objects
4)Schemas:Collections of objects ,such as tables,views,and sequences
2System Privileges
. More than 100 privileges are available;
. The database administrator has high-levle system privileges for tasks such as:
creating new user,removing user,removing tables,backing up tables
3 Creating user
the dba creates users by using the create user statement
create user user
identified by password;
e.g create user object scott
identified by tiger;
SQL> create user testuser
2 identified by test;
User created
SQL> conn testuser/test@orcl2000
Not logged on
SQL> grant access session to testuser;
grant access session to testuser
Not logged on
SQL> conn digit_cc/digit_cc@orcl2000
Connected to Oracle9i Enterprise Edition Release 9.2.0.1.0
Connected as digit_cc
SQL> grant create session to testuser;
Grant succeeded
SQL> conn testuser/test@orcl2000;
Connected to Oracle9i Enterprise Edition Release 9.2.0.1.0
Connected as testuser
4 user System privileges
once a user is created,the dba can grant specific system privileges to a user
grant privilege[,privilege...]
to user [,user|role,public...];
DBA can grant a user specific system privileges
grant create session,create table,create sequence,create view to scott;
5 creating and granting privileges to role
' Create a role
create role manager;
.grant privileges to a role
grant create table,create view to manager
.Grant a role to user
grant manager to kochar;
SQL> create role testrole;
Role created
SQL> grant create table,create view,create sequence to testrole;
Grant succeeded
SQL> grant testrole to testuser;
6 change your password
you can change your password by using the alter user statement;
alter user scott
indetified by lion;
7 object privileges
object privileges vary from object to object
an owner has all the privilege to the object
an owner can give specific privilege on that owner object
grant select on auther to testuser;
grant select on outher to testuser with grant option -- testuser also can grant it to
other user;
grant update(department_name,location_id)
on departments
to scott,manager;
8 how to revoke object privileges
--you use the revoke statement to revoke privileges granted to other users
--privileges granted to other users through the with grant option clause are also revoked.
revoke privilege {[,privilege...]|all} on object
from {user[,user....]|role|public}
[cascade constraints]
revoke select on author from user;
9 Database Links
Database link allow user to access data in the remote database;
SQL> create database link kjw1
2 connect to digit_cc identified by digit_cc
3 using 'orcl2000';
Database link created
SQL> select * from digit_cc.table_action@kjw1;
]]>
在一个分布式的环境里Q数据库链接是定义到其它数据库的路径的一个重要方法，使得q程处理天衣无缝?/p>
要获得数据库链接的更深奥的知识，查看Oracle8i SQL ReferenceQOracle8i SQL参考）和Oracle8i Concepts QOracle8i概念手册Q。详l资料的另一个极好的来源是Oracle8i Distributed Database SystemsQOracle8i分布式数据库pȝ手册Q?/p>
今天许多q行Oracle的机构有不止一个Oracle数据库。有时不原计划是否q样Q一个数据库中的数据可能与另一数据库中的数据关联。出现这U情冉|Q你可以链接q两个数据库使得用户或应用程序可以访问所有数据，好象它们在一个数据库中。当你这么做Ӟ你就有了一个分布式数据库系l?
如何两个数据库链接在一起呢Q用一个数据库链接来完成。数据库链接是定义一个数据库到另一个数据库的\径的对象。数据库链接允许你查询远E表及执行远E程序。在M分布式环境里Q数据库链接都是必要的?
单案?/p>
数据库链接的目的是定义一条到q程数据库的路径Q你可以通过在本地执行一条SQL语句来用那个数据库中的表和其它的对象。例如，你在一个远E数据库上有一个称之ؓ"geographic feature name"的表Q而你惛_已连接到你本地数据库的情况下讉K那些数据。数据库链接正是你所需要的。在建立它之前，你必L集如下信息：
一个网l服务名Uͼ你的本地数据库事例能够用它来与q程事例相连接远E数据库上的有效用户名和口o|络服务名称是每一个数据库链接必需的。每一ơ你从客hPC使用SQL*Plusq接C的数据库旉要用服务名U。在那些情况下，你提供给SQL*Plus的网l服务名U是通过在你的客h上的nsnames.ora文g中查扑֮们来解析的。在数据库链接中使用的网l服务名UC是如此，除非是那些名字是使用ȝ在服务器上的tnsnames.ora文g来解析?
在你定义数据库链接时指定的用户名和口令，用于建立与远E事例的q接。不需编码用户名和口令，建立数据库链接也是可能的甚至是值得选取的。既然这P现在我们注意q个最直接的例子?
下列语句建立了一个数据库链接Q它允许讉K客户帐户Q这个帐h事先在GNIS数据库徏好的Q?/p>
CREATE DATABASE LINK GNIS
CONNECT TO GUEST IDENTIFIED BY WELCOME
USING 'GNIS';
链接名称GNIS紧随LINK关键字。当q接到远E事例时QCONNECT TO...IDENTIFIED子句指定UEST/WELCOME作ؓ用户名和口o使用 。USING子句指定通过|络服务名称GNIS建立q接。用这一链接Q现在你可以在远E数据库上查询数据。例如：
SQL> SELECT GFN_FEATURE_NAME
2 FROM GNIS.FEATURE_NAMES@GNIS
3 WHERE GFN_FEATURE_TYPE='falls'
4 AND GFN_STATE_ABBR='MI'
5 AND GFN_COUNTY_NAME='Alger';
GFN_FEATURE_NAME
_________________
Alger Falls
Au Train Falls
Chapel Falls
Miners Falls
Mosquito Falls
Tannery Falls
..
在SELECT语句中@GNIS紧随表名Uͼ说明GNIS.FEATURE_NAMES表是在远E数据库Q应该通过GNIS链接讉KQ链接类型Oracle支持几种不同cd的链接。这些类型相互重叠，有时难以通过选项q行分类。当你徏立数据库链接Ӟ你需要从下面选取Q?
PublicQ公用）或Private Q私有）链接
权限c? Fixed UserQ固定用P, Connected UserQ连接用P?Current UserQ当前用P
Shared LinkQ共享链接）?Not Shared LinkQ非׃n链接Q?
每次创徏数据库链接时Q你要自觉不自觉地做q三U选择?
公用链接与私有链接相Ҏ
公用数据库链接对所有的数据库用户开放访问权。前面显C的是私有数据库链接Q它只对建立它的用户授权。公用数据库链接更ؓ有用Q因为它使你不必为每一个潜在用户创建单独的链接。ؓ了徏立一个公用数据库链接Q用如下显C的PUBLIC关键字：
CREATE PUBLIC DATABASE LINK GNIS
CONNECT TO GUEST IDENTIFIED BY WELCOME
USING 'GNIS';
即ɘq是一个公用链接，用户名仍旧固定。所有用这个链接的用户都作为用户GUESTq接到远E数据库?
使用数据库链接访问远E表
? 数据库链接GNISQ指明网l服务名Uͼ链接PROD事例到GNIS事例中的FEATURE_NAMES表?
权限c?/p>
当你建立一个数据库链接Ӟ关于你如何授权对q程数据库进行访问，有三U选择。这三种选择代表了数据库链接的另一U分cL法。这三种cd如下Q?
固定用户。ؓq程数据库链接指定用户名和口令，作ؓ数据库链接定义的一部分?
q接用户。在不指定用户名和口令时创徏的数据库链接?
当前用户。徏立数据库链接q指定CURRENT_USER关键字?
固定用户数据库链接是指在创徏链接时ؓq程数据库指定用户名和口令。这一链接不管什么时候用，也无使用Q都使用相同的用户名和口令登陆到q程数据库。到目前为止你在本文中所看到的都是固定用户链接?
固定用户链接Q尤其是公用固定用户链接的一个潜在问提是他们把远E系l上的同一帐户l了许多本地用户。从安全角度来说Q如果所有的本地用户在远E系l上拥有同一个帐P责Qp折中Q这取决于用L数量 。如果数据丢失，几乎不可能确定破坏是如何发生的。另一个潜在问题是公用固定用户链接对q程数据库的讉K权给了所有的本地数据库用戗?
如果你不惛_数据库链接中嵌入用户名和口oQOracle提供l你另一个非常有用的选择。你可以建立一个连接用户链接。连接用户链接是q样的链接，它通过M个正在用该链接的本地数据库的用L用户名和口o登陆到远E数据库。你可以通过单地I出用户名和口o来徏立一个连接用户链接。考虑如下定义Q?
CREATE PUBLIC DATABASE LINK GNIS
USING 'GNIS';
链接名是GNIS。它q接到远E数据库q接时用的|络服务名称是GNISQ但是没有指定用户名和口令。当你在查询中用这个链接时Q它向q程数据库发送你当前的用户名和口令。例如，如果你用AHMAD/SECRET 登陆C的本地数据库Q那么AHMAD/SECRET是你登陆到q程数据库时使用的用户名和口令?
Z使用一个连接用户链接，你必dq程数据库上有一个帐P了解q一Ҏ很重要的。不但这P而且你在两个数据库上应用同L用户和口令。如果本地登陆用AHMAD/SECRETQ那么登陆到q程数据库时也必M用同L用户名和口o。用连接用户链接时Q如果你的口令不同，你就无权登陆?
公用q接用户数据库链接尤其有用，因ؓ你可以徏立一个可被所有用戯问的链接Qƈ且所有用戯分别使用他或她自q用户名和口o授权。你获得责Q斚w的利益，没有远E数据库向你的本地数据库上的每一位用户开放。代h你必d两个数据库上建立用户帐户Qƈ且你必需信口o保持一致?
当前用户链接通过使用CURRENT_USER关键字徏立ƈ且与q接用户链接怼。只有当使用Oracle Advanced Security OptionQOracle高安全选项Q时Q你才能使用当前用户链接Q这个链接只Ҏ权用X.509认证的用h用?
׃n链接
׃n数据库链接是指该链接的多个用户可以共享同一个底层网l连接。例如，在有四位用户的MTSQ多U程服务器）环境下，每一个共享服务器q程都将与远E服务器有一个物理链接，q四位用户共享这两个链接?
表面上，׃n链接乍一听v来像是一件好事。在某些环境下的如此，但是Q当你考虑使用׃n链接Ӟ应当意识到这有许多局限性和警告Q?
如果你用一个专用的服务器连接来q接C的本地数据库Q链接只能在你从那些q接中创建的多重会话间共享?在MTS环境里，每一个共享服务器q程潜在地打开一个链接。所有的会话被同一׃n服务器进E提供ƈ且分享被那个q程打开的Q意共享链接。因为在MTS环境里的一个共享服务器q程能够服务于许多用戯接，׃n链接的用可能导致打开的链接远多于所必须的链接。用SHARED关键字徏立共享数据库链接。还必须使用AUTHENTICATED BY 子句在远E系l上指定一有效的用户名和口令。如下命令徏立一个共享的、公用的、连接用h据库链接Q?
CREATE SHARED PUBLIC DATABASE LINK GNIS
AUTHENTICATED BY DUMMY_USER IDENTIFIED BY SECRET
USING 'GNIS';
要获得创建链接和理分布式系l的更多资料Q请查阅Oracle Technology Network (http://otn.oracle.com/)?
使用AUTHENTICATED BY子句E微有些困扰Q但是由于实现共享链接的方式安全性决定它是必ȝ。这个例子中的用户名和口令DUMMY_USER/SECRET必须在远E系l上有效。然而，q程pȝ上用的帐户仍就是连接用L帐户。如果我以JEFF/SECRET登陆到我的本地数据库q用我刚徏好的׃n链接Q将会发生以下一pd事gQ?
Z打开链接QOracle使用DUMMY_USER/SECRET向远E数据库授权?然后QOracle试图使用HMAD/SECRET使我登陆到远E数据库。共享链接的主要目的是减两个数据库服务器之间的底层|络q接数量。它们最适合于MTS环境Q在那你拥有大量的通过q一链接讉Kq程数据库的用户。观念上Q你惌用户数量过׃n服务器进E的数量。那么你可以通过为每一׃n服务器进E打开一个链接而不是每位用h开一个链接的ҎQ节省资源?
查找关于数据库链接的资料
你可以从几个数据字典视图中获得徏立好的数据库链接的资料。DBA_DB_LINKS视图为每一定义的链接返回一行。OWNER 列和DB_LINK列分别显CZq一链接的所有者及名称。对公用数据库链接，OWNER列将包含'PUBLIC'。如果你建立固定用户链接Q用户名应在DBA_DB_LINKS视图的USERNAME列里Q但是口令只能从SYS.LINK$视图中看到。默认情况下Q只有具有SELECT ANY TABLEpȝ权限的DBA能够讉KSYS.LINK$视图查看口o。你应该保护讉K那个视图的权限。ALL_DB_LINKS 视图?USER_DB_LINKS视图?DBA_DB_LINKS视图相类?它们分别昄了你能够讉K的所有链接及你所拥有的全部链接。最后，V$DBLINK动态性能视图向你昄ZQ意给定时间你-当前用户Q打开的全部数据库链接?
全局性的数据库名U?
在分布式环境里，Oracle你的数据库链接名应与它们q接到的数据库的全局性名U相匚w。因此如果你正在q接到名UCؓGNIS.GENNICK.ORG的数据库Q你应当你的数据库链接命名为GNIS.GENNICK.ORG
为确定数据库的全局性名Uͼ以SYSTEM登陆q查询GLOBAL_NAME视图Q?
SQL> SELECT * FROM GLOBAL_NAME;
GLOBAL_NAME
_______________
GNIS.GENNICK.ORG
׃历史的原因，默认情况下，全局性名UC数据库链接名U的之间的链接不是强制性的。不q，你可以通过讄GLOBAL_NAMES的初始化参数为TRUE来改变这一行ؓ。例如：
SQL> SHOW PARAMETER GLOBAL_NAMES
NAME TYPE VALUE
________________________________________________________
global_names boolean TRUE
用于产生q个范例的事例要求你使用的数据库链接名，必须与目标数据库的全局性数据库名称相匹配。注意与一些Oracle文档中说的相反，关键是你的本C例的GLOBAL_NAMES讄。如果你的本C例中GLOBAL_NAMES=FALSEQ你p够用数据库链接Q而不用管它们是否与远E数据库的全局性名U相匚w。ȝ来说Q如果你讄GLOBAL_NAMES=TRUEQ你应该在你的所有事例中一律这么做?br />
]]>
1) automatically generatess unique numbers
is a sharable object
is typically used to create a primary key value
replaces applicaition code
speeds up the efficiency of accessing sequence
create sequence sequence
[increment by n]
[start with n]
[{maxvalue n |nomaxvalue}]
[{minvalue n |nominvalue}]
[{cycle|nocycle}]
[{cache n |nocache}]
create sequence dept_deptin_seq
increment by 10
start with 120
maxvalue 9999
nocache
nocycle
2) Confirming Sequences
verify your sequence values in the user_sequences data dictionary table
select sequence_name,min_value,max_value,increment_by,last_number
from user_sequences;
the last_number display the next available sequence number if nocache is specified
3)nextval and currval Pseudocolumns
--nextval return thee next available sequence value,it return a unique value every time
it si referenced,even for different ueer;
--currval obtains the current sequence value;
--nextval must be issued for that sequence before curval contains a value;
4) Using a Sequence
-- Caching sequence values in the memory give faster access to these values;
-- Gaps in sequence value can occur when
a rollback occurs
b the system crashes
c A sequence us used in another table;
5) alter sequence test increment by 10;
you can change all properties of the sequence except the start with .
6) remove sequence
drop sequence test;
2 index
1) how are indexes created
Automatically : a unique index is created automatically when you create primary key or
unique constraint in a table definition,
Manually: user can create nounique index on column to speed up access to the rows.
create index testindex on autoer(lanme);
2) When to Create an index
ypu should create an index if:
. a column contains a wide range of values
. a column contains a large number of null values
. one or more columns are frequently used together in where clause or a join condition;
. The table is large and most queries are expected to retrieve less than 2 to 4 percent
of the rows;
3) When not to create an index
this usually not worth creating an index if:
. the table is small
. The columns are not often used as a condition in the query.
. Most queries are expected to retrieve more than 2 to 4 percent of the rows in the
table
. the indexed columns are referenced as part of an expression.
4)Confirming indexes
. The user_indexes data dictionary view contains the name of the index and tis uniquess
. the user_ind_columns view contains the index name,the table name,and the column name.
select ic.index_name,ic_column_name,ic.column_position,ic_col_pos,ix.uniqueness
from user_indexed ix,user_ind_columns ic
where ic.index_name=ix.index_name
and ic.table_name='employees';
5)Z函数的烦?br /> . a function-based index is an index based on expressions
. The index expression is built form table columns,constraints,SQL functions and user-
defined functions
create index testindex2
on autors (upper(au_fname));
select * from authors
where upper(au_fname) like 'B%';
6) remoe index
drop index index_name;
3 synonyms
Simplify access to objects by creating a synonym
. Ease referring to a table ownerd by anther user
. Shorten lengthy object names;
create [publi] synonym synonym for object;
]]>
index by binary_integer;
ename_table ename_table_type;
begin
select ename into ename_table(-1) from emp
where empno=&no;
dbms_output.put_line('雇员名：'||ename_table(-1));
end;
set serveroutput no
declare
type area_table_type is table of number
index by varchar2(10);
rea_table area_table_type;
begin
area_table('beijing'):=1;
area_table('shanghai'):=2;
area_table('guangzhou'):=3;
dbms_output.put_line(area_table.first);
dbms_output.put_line(area_table.last);
end;
2) 嵌套?br /> 索引表类型不能作为篏得数据类型用，但是嵌套表可以作cȝ数据cd使用?br />当用嵌套表元素Ӟ必须先用其构造方法初始化其嵌套表Q?br /> a 在pl/sql 块中使用嵌套?br /> declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
ename_table:=eanme_table_type('2','2','3');
select ename into ename table(2) from emp where empno=&no;
dbms_ouput.put_line(ename_table(2));
end;
b 在表中用嵌套表
create type phone_type is table of varchar2(20);
create table employee(
id number (4),name varchar2(10),sal number(6,2),
phone phone_type
)nested table phone store as phone_table;
-- 为嵌套表插入数据
insert into employee values(2,'scott',200,phone_type('2222','333333'));
Q－索嵌套表累得数据
set erveroutput on
declare
phone_table phone_type;
begin
select phone into phone_table
from employee where id=1;
for i in 1..phone_table.count loop
dbms_output.put_line(phone_table(i));
end loop;
end;
-- 更新嵌套表列的数?br /> delcare
phone_table phone_type:=('44444','555555');
begin
update employee set phone=phone_table
where id=1;
end;
3) 变长数组
在用varray 时必L定最大个敎ͼ和数据类?在用其元素时必进行初始化
type ename_table_type is varray(20) of emp.ename%type;
ename_table ename_table_type:=ename_table_type('1','2');
-- 在快中用varray
declare
type ename_table_type is varray(20) of emp.enameQtypeQ?br /> ename_table ename_table_type:=ename_table_type('mary');
begin
select ename into ename_table(1) form emp
where empno=$no;
end;
--在表列中使用varray
create type phone type is varray(20) of varchar2(20);
create table employee(
id number(4),name varchar2(10),
sal number(6,2),phone phone_type);
3)记录?br /> 记录表结合了记录和集合的优点
declare
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * from into emp_table(1) from emp
where empno=&no;
dbms_output.put_line(emp_table(1).ename);
end;
4)多维集合
1 多varray
declare
--define 一l集?br /> type al_array_type is varray(10) of int;
--定义二维集合
type nal_varray_type is varray(10) of a1_varray_type;
--初始化二l集?br /> nvl nal_varray_type:=nal_varray_type(
a1_varray_type(1,2),
a1_varray_type(2,3)
)
beign
for i in 1..nal_varray_type.count loop
for j in 1..a1_array_type.count loop
dbms_out.putline(nvl(i)(j));
end loop;
end loop;
end;
2 使用多嵌套?br /> table a1_table_type is table of int;
table nvl_table_type is table of a1_table_type;
nvl nvl_table_type:=nvl_table_type(
a1_table_type(1,2),
a1_table_type(2,3)
);
2 集合Ҏ
1) exist
if ename_table.exists(1) then
ename_table(1):='scott';
2) count q回当前集合变量中的元素M?br /> ename_table.count
3) limit q回集合元素的最大个敊W?只有varray ?br /> 4)first and last
ename_table.first
ename_table.last
5) prior 和next
ename_table.prior(5); Q－q回元素5的前一?br /> ename_table.next(5); -- 后一?br /> 6) extend
使用于varray ?嵌套表?br /> extend add a null value
extend (n) add n null value
extend (n,i)add n i value
declare
type ename_table_type is varray(20) of varchar2(20);
ename_table ename_table_type;
begin
ename_table:=ename_table_type('mary');
ename_table.extend(5,1);
dbms_output.put_line(ename_table.count);
end;
7) trim
trim remove one element from the tail of the collection.
trim(n) remove n element from the tail of the colleciton.
8)delete
delete: delete all the elements
delete(n) :delete the nth elements
delete(m,n): delete the elements from m to n
3 集合赋?br /> 1)一个集合的数据赋值给另一个集?clear the destination collectins and set the original collection
delcare
type name_varray_type is varray(4) of varchar2(10);
name_array1 name_varray_type;
name_array2 name_varray_type;
begin
name_array1:=name_varray_type('scott','smith');
name_array2:=name_array_type('a','b','c');
name_array1:=name_array2;
end;
type name_array1_type is varray(4) of varchar2(10);
type name_array2_type is varray(4) of varchar2(10);
name_array1 name_array1_type;
name_array2 name_array2_type;
h相同的数据类型，单具有不同的集合cd不能构赋?br /> 2) l集合赋城null ?br /> 可以使用delete ?trim
也可以?I集合赋l目表集?br /> type name_varray_type is varray(4) of varchar2(10);
name_array name_varray_type;
name_empty name_varray_type;
name_array:=name_varray_type('1','2');
name_array:=name_empty;
3) 使用集合操作赋和比较集合都是10g 的内容，p176 先略q?br />4 扚wl定
执行单词sql 操作能传递所有集合元素的数据?br /> 1 forall 语句
用于insert update 和delete操作。在oracle9i 中forall 语句必须hq箋的元?br /> 1) using forall on insert
declare
type id_table_type is table of number(6)
index by binary_integer;
type name_table_type is table of varchar2(2)
index by binary integer;
id_table id_table_type;
name_table name_table_type;
begin
for i in 1..10 loop
id_table(i):=i;
name_table(i):='Name'||to_char(i);
end loop;
forall i in 1..id_table.count
insert into demo demo values(id_table(i),name_table(i));
end;
2)using forall on using update
forall i in 1..id_table.count
upate demo set name:=name_table(i)
where id:=id_table(i);
3)using forall on using delete
forall i in 1..id_table.count
delete from demo where id:=id_table(i);
4) using forall on part of the collection
for i in1..10 loop
id_table(i):=i;
name_table(i):="name"||to_char(i);
end loop;
forall i in 8..10 l
insert into demo values(id_table(i),name_table(i));
2 bulk collect
is fit for select into ,fetch into and dml clause
1) using bulk collect
declares
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * bulk collect into emp_table
from emp where deptno=&no;
for i in 1..emp_tablee.count loop
dbms_output.put_line(emp_table(i).ename);
end loop;
2) 在dml 的返回字句用bulk collect 字句
declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
deletee from emp where deptno=&no
returning ename bulk_collect into ename_table;
for i in 1..ename_table.count loop
dbms_output.put(ename_table(i));
end loop;
end;
end;
end;
]]>
to restrict data access
to make complex query easy
to provide data independence
to provide defferent view of the same data
2 Creating a View
1)create [or replace] [force|noforce] view view
as subquery
force : create view wether the referenced object existed or not
desc view_name;
2)create a view by using column aliases in the subquery
create view salv50
as select employee_idIO_NUMBER,last_name NAME,slaary*12 ANN_SALARY
from employees
where department_id=50;
3 Modigy a View
1) Modigy the emplvu80 view by using create or replace view clause.Add an alias for each
column name;
create or replace view empvu80
(id_number,name,sal,department_id)
as select employee_id,first_name||" "||last_name,salary.department_id
from employees
where department_id=80;
column aliases in the create view clause are listed in the same order as the columns in
the subquery
note : alter view_name is not a valid command.
4 Create a Complex View
Create a complex view that contains group functions to display values from two tables
create view dept_sum_vu
(name,minsal,maxsal,avgsal)
as
select d.department_name,min(e.salary),max(e.salary),avg(e.salary)
from employees e,departments d
where e.department_id=d.department_id
group by d.department_name;
5 Rules for performs DML operaton on a view
1) You can perform DML operation on simple views
2) You can not romove a row if the view contains the following:
--group functions
--a group by clause
--the distince keyword
-- rownum keyword
-- column defined by expressions
6 Using the with check option Clause
1) you can ensure that dml operatons performed on the view stay within the domain of the
view by using the with check option clause.
creaate view test1
as
select * from emp where qty>10;
with check option;
update testview1 set qty=10
where ster_id=6830;
--when you doing the following update operation
update testview1 set qty=5 where id=10;
-- an error will report
--you violate the where clause
2)Any attempt to change the department number for any row in the view fails because it
violates the with check option constraint
create or replace view empvu20
as
select * where department_id=20
with check option constriant empvu20_ck;
7 Denying DML Operations
1 You can ensure that no dml operations occur by adding the with read only option to your
view definition.
2)Any attempt to a DML on any row in the view resuls in an oralce server error.
8 remove veiw
drop view_name
9 inline view
1) an inline view is a subquery with an alias that you can use within a sql statement.
2) a named subquery in the from clause of the main query is an exqmple of an inline view
3) an inline view is not a schema object.
10 Top-N Analysis
1)Top_N querise ask for the n largest or smallest values of a column.
2)Both largest values and smallest values sets considered Top-N queries
select * from (select ster_id,qty from sales);
example
To display the top three earner names and salaries from the employees
select rownum as rank,last_name,salary
from (select last_anme,slary from employee
order by slary desc)
where rownum<=3;
]]>
1Q?索引?br /> type ename_table_type is table of emp.ename%type
index by binary_integer;
ename_table ename_table_type;
begin
select ename into ename_table(-1) from emp
where empno=&no;
dbms_output.put_line('雇员名：'||ename_table(-1));
end;
set serveroutput no
declare
type area_table_type is table of number
index by varchar2(10);
rea_table area_table_type;
begin
area_table('beijing'):=1;
area_table('shanghai'):=2;
area_table('guangzhou'):=3;
dbms_output.put_line(area_table.first);
dbms_output.put_line(area_table.last);
end;
2) 嵌套?br /> 索引表类型不能作为篏得数据类型用，但是嵌套表可以作cȝ数据cd使用?br />当用嵌套表元素Ӟ必须先用其构造方法初始化其嵌套表Q?br /> a 在pl/sql 块中使用嵌套?br /> declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
ename_table:=eanme_table_type('2','2','3');
select ename into ename table(2) from emp where empno=&no;
dbms_ouput.put_line(ename_table(2));
end;
b 在表中用嵌套表
create type phone_type is table of varchar2(20);
create table employee(
id number (4),name varchar2(10),sal number(6,2),
phone phone_type
)nested table phone store as phone_table;
-- 为嵌套表插入数据
insert into employee values(2,'scott',200,phone_type('2222','333333'));
Q－索嵌套表累得数据
set erveroutput on
declare
phone_table phone_type;
begin
select phone into phone_table
from employee where id=1;
for i in 1..phone_table.count loop
dbms_output.put_line(phone_table(i));
end loop;
end;
-- 更新嵌套表列的数?br /> delcare
phone_table phone_type:=('44444','555555');
begin
update employee set phone=phone_table
where id=1;
end;
3) 变长数组
在用varray 时必L定最大个敎ͼ和数据类?在用其元素时必进行初始化
type ename_table_type is varray(20) of emp.ename%type;
ename_table ename_table_type:=ename_table_type('1','2');
-- 在快中用varray
declare
type ename_table_type is varray(20) of emp.enameQtypeQ?br /> ename_table ename_table_type:=ename_table_type('mary');
begin
select ename into ename_table(1) form emp
where empno=$no;
end;
--在表列中使用varray
create type phone type is varray(20) of varchar2(20);
create table employee(
id number(4),name varchar2(10),
sal number(6,2),phone phone_type);
3)记录?br /> 记录表结合了记录和集合的优点
declare
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * from into emp_table(1) from emp
where empno=&no;
dbms_output.put_line(emp_table(1).ename);
end;
4)多维集合
1 多varray
declare
--define 一l集?br /> type al_array_type is varray(10) of int;
--定义二维集合
type nal_varray_type is varray(10) of a1_varray_type;
--初始化二l集?br /> nvl nal_varray_type:=nal_varray_type(
a1_varray_type(1,2),
a1_varray_type(2,3)
)
beign
for i in 1..nal_varray_type.count loop
for j in 1..a1_array_type.count loop
dbms_out.putline(nvl(i)(j));
end loop;
end loop;
end;
2 使用多嵌套?br /> table a1_table_type is table of int;
table nvl_table_type is table of a1_table_type;
nvl nvl_table_type:=nvl_table_type(
a1_table_type(1,2),
a1_table_type(2,3)
);
2 集合Ҏ
1) exist
if ename_table.exists(1) then
ename_table(1):='scott';
2) count q回当前集合变量中的元素M?br /> ename_table.count
3) limit q回集合元素的最大个敊W?只有varray ?br /> 4)first and last
ename_table.first
ename_table.last
5) prior 和next
ename_table.prior(5); Q－q回元素5的前一?br /> ename_table.next(5); -- 后一?br /> 6) extend
使用于varray ?嵌套表?br /> extend add a null value
extend (n) add n null value
extend (n,i)add n i value
declare
type ename_table_type is varray(20) of varchar2(20);
ename_table ename_table_type;
begin
ename_table:=ename_table_type('mary');
ename_table.extend(5,1);
dbms_output.put_line(ename_table.count);
end;
7) trim
trim remove one element from the tail of the collection.
trim(n) remove n element from the tail of the colleciton.
8)delete
delete: delete all the elements
delete(n) :delete the nth elements
delete(m,n): delete the elements from m to n
3 集合赋?br /> 1)一个集合的数据赋值给另一个集?clear the destination collectins and set the original
collection
delcare
type name_varray_type is varray(4) of varchar2(10);
name_array1 name_varray_type;
name_array2 name_varray_type;
begin
name_array1:=name_varray_type('scott','smith');
name_array2:=name_array_type('a','b','c');
name_array1:=name_array2;
end;
type name_array1_type is varray(4) of varchar2(10);
type name_array2_type is varray(4) of varchar2(10);
name_array1 name_array1_type;
name_array2 name_array2_type;
h相同的数据类型，单具有不同的集合cd不能构赋?br /> 2) l集合赋城null ?br /> 可以使用delete ?trim
也可以?I集合赋l目表集?br /> type name_varray_type is varray(4) of varchar2(10);
name_array name_varray_type;
name_empty name_varray_type;
name_array:=name_varray_type('1','2');
name_array:=name_empty;
3) 使用集合操作赋和比较集合都是10g 的内容，p176 先略q?br />4 扚wl定
执行单词sql 操作能传递所有集合元素的数据?br /> 1 forall 语句
用于insert update 和delete操作。在oracle9i 中forall 语句必须hq箋的元?br /> 1) using forall on insert
declare
type id_table_type is table of number(6)
index by binary_integer;
type name_table_type is table of varchar2(2)
index by binary integer;
id_table id_table_type;
name_table name_table_type;
begin
for i in 1..10 loop
id_table(i):=i;
name_table(i):='Name'||to_char(i);
end loop;
forall i in 1..id_table.count
insert into demo demo values(id_table(i),name_table(i));
end;
2)using forall on using update
forall i in 1..id_table.count
upate demo set name:=name_table(i)
where id:=id_table(i);
3)using forall on using delete
forall i in 1..id_table.count
delete from demo where id:=id_table(i);
4) using forall on part of the collection
for i in1..10 loop
id_table(i):=i;
name_table(i):="name"||to_char(i);
end loop;
forall i in 8..10 l
insert into demo values(id_table(i),name_table(i));
2 bulk collect
is fit for select into ,fetch into and dml clause
1) using bulk collect
declares
type emp_table_type is table of emp%rowtype
index by binary_integer;
emp_table emp_table_type;
begin
select * bulk collect into emp_table
from emp where deptno=&no;
for i in 1..emp_tablee.count loop
dbms_output.put_line(emp_table(i).ename);
end loop;
2) 在dml 的返回字句用bulk collect 字句
declare
type ename_table_type is table of emp.ename%type;
ename_table ename_table_type;
begin
deletee from emp where deptno=&no
returning ename bulk_collect into ename_table;
for i in 1..ename_table.count loop
dbms_output.put(ename_table(i));
end loop;
end;
end;
end;
]]>
1) Constrains enforce on the table level
2) Constrains the deletion of a table if there are dependencies
2 Constrain Guidelines
1) Name a constraint or the oracle generate a name by the sys_cn format
2) Create a constraint either
--At the same time as the table is created.or
--After the table has been created
3)Define a constraint at the column or table level
4)view constraint in the data dictionary
3 Crete a constraint
create table test2
(id int not null,-- column level
lname varchar(20),
fname varchar(20),
constraint uk_test2_1 unique(lname,fname))--table level
4 The not null Constraint
create table employees(
employee_id number(6),
last_name varchar2(25) not null --system named
hire_date DATE
constraint emp_hire_date not null --User named
5Foreign key
create table test3
(rid int,
name varchar(30),
constraint fk_test3_1 foreign key(rid) reference test2(id));
froeign key constraint keywords
foreign key :Define the column in thee child table at the table constrain level.
references :Identifies the table and column in the parent table.
on delete cascade: Delete the dependent rows in the child table when a row in the
parent table is deleted
on delete set null:Convert the dependent foreign key values to null when a row in the
parent table is deleted.
--parent table referenced table
--child table refernce other table
6 The check Constraint
Define a condition that each row must be satify
alter table test3
add constrain ch_test3 check(name like 's%')
7 Dropping a Constraint
1) Remove the manager constraint form the employee table
alter table test3
drop constriant test3_manager_fk
2) Remove the primary key constraint on the departments table and drop the associated
foreign key constraint on the employees.department_id column
alter table departments
drop primary key cascade
8 Disabling and enable Constraints
1)Execute the disable clause of the alter table statment to deactive an integrity
constraint
2)Apply the cascade option to disable dependent integrity constrints
alter table employees
disable constraint emp_emp_id_pl cascade
3) enabling Constraints
.Active an integrity constraint currently disabled in the table definition by using the
enable clause.
alter table employees
enable constraint emp_emp_id_pk;
a unique or a primary index is automatically created if you enable a unique key or a
primary key constraint
8 View Constraints
select constraint_name,constriant_type,serch_condition
from user_constraints
where table_name='employees'
9 view the columns associated with constraints
select constraint_name,column_name
from user_cons_columns
where table_name='employees'
]]>
a Are a collection of tables created and maintained by the user
b Contain user information
2) Data Dictionary
a is a collection of table created and maintained by the Oracle Server
b Contain database information
2 Querying the Data Dictionary
1)see the names of the table owned by the user
select table_name from user_tables;
2) view distinct object types ownered by the user
select distinct object_type from user_object;
3) view tables ,view ,synonyms and sequences owned by the user
select * from user_catalog
3 Creating a Table by Ussing a Subquery Syntax
create table tt3
as
select * from authors
4 Teh alter table Statement
1) Add a new column
alter table tt2
add(fname varchar2(20) default 'unkonown',
address varchar2(30) null);
2)Modigying a Column's data type size and default value
alter table dept80
modigy (last_name varchr2(30))
A change to thee default value affects onlly subsequent insertion to the table
3) drop a column
alter table dept80
drop column job_id;
The set unseed Option
a you use the set unused optoin to mark one or more columns as unused
b you use the drop unused colimns options to remove the columns that are marked as
as unused
alter table tt2
set unused colun fnamel;
alter table table
drop unused columns
5 Dropping a Table
1) All data and structure in the table is deleted
2) Any pending transaction are committed
3) All indexes are dropped
4) You cannot roll back the drop table statement
6 Changing the Name of an Object
rename dept to detail_dept;
you must be the owner of the object
7 Truncate a Table
Remove all rows from the table
release the storage space used by that table
you cannot rollback row when using truncate
alternatly ,you can remove row by using delete statement
]]>
add new rows to a table
modify existing row in a table
remove existing rows from a table
2) A transaction consist a collection dml statements form a logic unit of work
2 Using Explicit Default Values
1) default with insert
insert into departments
values(200,'ddd',default)
2) default with update
update departments
set manager_id=default where department_id=10
3 The Merge Statement
1)Provide the ability to conditionaly update or insert data into database
2)Perform a update if the row exists and an insert if it is a new row
a Avoid update separatly
b increase performance and ease of use
c is useful in data warehousing application
example
merge into copy_emp c
using employees e
on (c.employee_id=e.employee_id)
when mathched then
update set
c.first_name=e.first_name
c.last_name=e.last_name
..............
c.department_id=e.department_id
when not matched then
insert values(e.employeeid,e.first_name,......e.department_id);
4 Database Transactions
1)Begin when the first dml statement is executed
2)end with one of the following events
a a commit or rollback statement is issued;
b a ddl or dcl statement execute (commit automatically)
c the user exist isqllplus
d the system crashes
3) advantage of commit and rollback statemnt
With commit and rollback statement ,you can
a ensure data consistence
b Preview data change before making change permant
c group logic relate operatons
5 State of The Data Before commit or rollback
1) the previous state of the data can be recovered
2) The current user can review the result of the dml operation by using the select statment
3) other user can not view the result of the dml
4) the affected was locked ,other user cannot change the data within the affecteed row
6 Read Consistency
1) Read consistency guarantees a consistent view of the data at all times
2) Changes made by one user do not confilict with changes made by another user
3) Read consistency ensures that on the same data
a Readers do not wait for writers
b Writers do not wait for readers
7Locking
1) Prevent destructive interaction between concurrent transactions
2) Reqire no user action
3) Automatically use the lowest level of restrictiveness
4) Are held for the duration of the transaction
5) Are of two types:explicit locking an implicit locking
8 Implicit Locking
1)Two lock modes
a Exclusive :Locks out other users
b Share: Allows other users to accesss
2)High level of data concurrency
a DML:Table share,row exclusive
b Queries: No locks required
c DDL:Protects object definitions
3)Locks held until commit or rollback
]]>
a Enclose subqueries in parenttheses
b placce subqueries on the right side of the comparision condition
c the order by clause in the subquery is not needed
d using single-row operators with single-row subqueries and use multiple -row operator with multiple-row subqueries .
single-row subqueries can work as a expression,and muitiple-row subqueries can only be used with in all any ,i will talk it later
select last_name where job_idd=(select job_id
from employees
where imployee_id=141)
2 The HAVING CLause with Subqueries
a The Oracle server execute subqueries first
b The Oracle return result into the HAVING clause of the main query
select department_id,min(salary)
from employee
group by department_id
having min(salary)>
(select min(salary)
from employees
where department_id=50);
3 Multiple-Row Subqueries
a Return more than one row
Using mutiple-row comparsion operator
select employee_id
from employees
where salary<any
(select salary
from employees
where job_id='ddd')
select employee_id
from employees
where salary<all
(select salary
from employees
where job_id='ddd')
select emp.last_name
from employees emp
where emp.employee_id not in
(select mgr.manager_id
from employees mgr)
]]>
select table1.column,table2,column
from table1,table2
where table1.column1=table2.column2 .
2 outjoin
1)You use an outer join to also see rows that do not meet the join condition
2)The Outer join operator is the plus sign(+)
a left join
select tabl1.column,table2,column
from table1,table2
where table1.column(+)=table2.column
b right join
select table1.column,table2.column
from table1,table2
wheretable1.coulmn=table2.column(+)
3) self join
select worker.last_name||'works for'||manager.last_name
from employees owrker,employees manager
where worker.manager_id=manager.employee_id;
3 Joining Tables Using SQL:1999 Syntax
Use a join to query data from more than one table
1) Creationg Cross Joins
a The cross join clause produces thee cross product of two tables
b This is the same as Cartesian product between the two tables
select last_name,department_name
from employees
ccross join departments
2) Creating Natual Joins
a The Natual join clause is bassed on all columns in the two tables that have the same name
b it select rows from the two tables that have the equal values in all matched columns
c if the columns having the same name and have the different data types in an error is returned.
select department_id,department_name,location_id,city
from departments
natual join locations
3) using clause
select e.employee_id,e.last_name
from employees e join departments d
using (department_id);
4) Creating joins with thee on clause
a The join condition for thee natual join is basically an equaljoin of all column with the same name.
b To specify arbitrary condition or specify columns to join, the on clause is userd
c The join condition is separated from other search conditions
d The on claus make code easy to understand.
select e.employee_id,e.last_name,e.department_id,
from employees e join departments d
on (e.department_id=d.department_id);
from employe
join departments d
on d.department_id=e.department_id
join locations l
on d.location_id=l.location_id
5) INNER Versus OuTER Joins
a In SQL:1999,the join of two tables returning only matched rows is an inner join
6) FULL OUTER JOIN
select e.last_name,e,department_id,d.department_name
from employees e
full outer join departments d
on (e.department_id=d.department_id);
]]>
2 ||
3 isql*plus http://127.0.00.1/isqlplus
4 desc author
5 initcap('SQL Course')
INSERT('JellwWord','W') 6
LPAD (salary,10,'*') *****24000
RPAD (salary,10,'*') 24000*****
TRIM ('H' from 'HolloWorld') olloWord
substr('helloword',1,5) hello
substr('helloword',-1,5) oword
6 Number Functions
round(45.926,2) 45.93
round(45.926,-2) 0
round(55.926,-2) 100
trunc(45.926,2) 45.92
mod(1600,300) 100
7 data function
systdate
(sysdate-hire_date)/7 as weeks
months_between number of months between two dates
months_between ('01-sep-95','11,jan-94') 19.6774194
add_months add calendar months to date
add_months('11-JAN-94',6) '11-JUL-94'
next_day next day of the date specified
next_day('01-SEP-95','FRIDAY') '08-SEP-95'
last_day last day of the month
last_day('01-feb-95') '28-feb-95'
round round date
assume sysdate='25-jul-95'
round(sysdate,'month') 01-aug-95
round(sysdate,'year') 01-JAN-96
trunc truncate date
trunc(sysdate,'month') 01-Jul-95
trunc(sysdate,'month') 01-JAN-95
8 Conversion Functions
1) implicit data typ conversion
varchar2 or char ---number
varchar2 or char ---date
numbeer ---varchar2
date ---varchar2
2) to_char(date,'format')
format:
YYYY Full year in numbers
YEAR Year spelled out
MM Two-digit value for month
MONTH Full name of the month
MON THree-letter abbreviation of the month
DY Three-letter abbreviation of the day of the week
DAY Full name of the day of hte week
DD Numberic day of the month
HH24:MI:SS AM 15:45:32:PM
DD "of" MONTH 12 of october
3) to_char function with number
TO_CAHR(number,'format_model')
These are some of the format elements you can use with the to_char function to display number as a character.
9 Reqresents a number
0 Forces a zero to be displayed
$ Places a flationg dollar sign
L Uses the floating local currency symbol
. Prints a decimal point
, Print a thousand director
select to_char(qtym,"$999.99")
4) Using t_number and to _date functions
a converting a character string to a number format using to_number function
to_number(char,"format")l
b converting a character string to a date format
to_date(char,"format")
5 Nesting Functions
.Single-row function can be nested to many level
.Nested function can be evaluated from deepest level
6General Function
These function work with any data type and pertain to using nulls
nvl(expr1,expr2);
nvl2(expr1,expr2,expr3)
nullif(expr1,expr2)
coalesce(expr1,expr2,,,,exprn)
1) nvl function
convert a null to an actual function
a Data type can be used are data character and number
b Data types must match
(set wrap off
set line 1000
)
2)Using the COALESCE Function
a The advantage of the coalesce function over nal function is that coalesce function can take multiple alternative value
b If the first value is not null, it return that expression,otherwise,it does a coalesce of remaining expressions
6 Conditional Expressions
a Provide the use of if-then-else logic
b use two methods: case expression decode function
select last_name,job_id,salary,
case job_id when 'it' then 1*salary
when 'manager' then 1.2*salary
else salary end;
from employee.
select last_namek,job_id,salary,
decode(job_id,'it' ,1*salary,
'manager',1.2*salary,
salary)
from employees
]]>
Group functions operatee on sets of rows to give one result per group
1)agg,count,max,min,stddev,sum,variance
select avg(salary),max(salary),min(salary),sum(salary)
from employees
where job_id like '%REP%'
select count(*) from
select count(address) from authors
count the valid count of the address (exclude the null value)
2) Using theDISTINCT Keyword
count(distinct expr) return thee number of the distinct non-null value of the expr
select count(distincee department_id) from employees
3)Group functions and null values
group functions ignore null values in the clumn
4) Using thee NVL Function with Group Functions
The nul function force group funtion to include null values
select avg(nvl(commission_pct,0)) from employees
2 Creating Groups of Data
1)
a Divide rows in a table into smaller groups by using the group by clause
b All coulmns in the select list that are not in group function must be in the group by clause
select department_id,avg(salary)
from employees
group by department_id;
2) Grouping by More Than One Column
3) Ilegal Queries Using Group Functions
a You cannot use thee where clause to restrict groups
b You use thee having clause to restrict groups
c you cannot use group functions in the where clause
4)Excluding Group Resdults:The Having Clause
Use the HAVING clause to restrict groups
a Rows are grouped
b The group functions is applied
c Groups matcching the Having clause are display
select department_id,max(salary)
from employees
group by department_id
having max(salary)>10000
5) Nesting Group function
select max(avg(salary))
from employees
group by department_id;
]]>
v_sal number(6,2);
begin
select sal into v_sal from emp
where lower(ename)=lower('&&name');
if v_sal<2000 then
update emp set sal=v_val+200
where lower(ename)=lower('&name');
end if;
end;
2 二重条g分支
if v_comm<>0 then
.....
else
........
end if;
3 多重条g分支
IF THEN
ELSIF THEN
ELSIF THEN
ELSE
END IF;
2 case 语句
1 在case 语句中用单一选择W进行等值比?br /> declare
v_deptno emp.deptno%type
begin
v_deptno:=&no;
case v_deptno
when 10 then
update emp...
when 20 then
update ......
else
dems_out.put_line('不存在该部门');
end case;
end;
2 在case 语句中用多U比较条?br /> declare
v_sal emp.sal%type
v_ename emp.ename%type
begin
select ename ,sal into vv_ename,v_sal
from emp where empno=&no;
case
when v_sal<1000 then
update emp set ...
when v_sal<2000 then
end case;
3 循环语句
1 基本循环
declare
i INT:=1;
begin
loop
insert into temp valuse(1);
exit when i=10;
i:=i+1;
end loop;
end;
2 while 循环
while i<=10 loop
insert into tem valuse(i);
i:=i+1;
end loop;
3for 循环
for i in reverse 1..10 loop
insert into temp values(1);
end loop;
4 序控制语句
1 goto
goto label_name;
loop
...
goto end_loop;
<<end loop>>
dbms_output
2 null 语句不会执行M操作Qƈ且会直接控制传递道下一条语?br /> if v_sal<3000 then
update emp set .....
else
null;
end if;
]]>