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recursion递归

断点 — Sat, 24 Jul 2010 08:25:00 GMT

--递归�Q�树状结构的存储与展�C?br /> drop table article;
create table article
(
id number primary key,
count varchar2(4000),
pid number,
isleaf number(1), --0 代表非叶子节点，1代表叶子节点
alevel number(2)
);

insert into article values(1,'蚂蚁大战大象',0,0,0);
insert into article values(2,'大象被打��下',1,0,1);
insert into article values(3,'蚂蚁也不好过',2,1,2);
insert into article values(4,'瞎说',2,0,2);
insert into article values(5,'没有瞎说',4,1,3);
insert into article values(6,'怎么可能',1,0,1);
insert into article values(7,'怎么没有可能',6,1,2);
insert into article values(8,'可能性是很大�?,6,1,2);
insert into article values(9,'大象�q�医院了',2,0,2);
insert into article values(10,'护士是蚂�?,9,1,3);
commit;

蚂蚁大战大象
    大象被打��下�?br />         蚂蚁也不好过
        瞎说
            没有瞎说
        大象�q�医院了
            护士是蚂�?br />     怎么可能
        怎么没有可能
        可能性是很大�?br />

--用存储过�E�展现树状结构�?br /> create or replace procedure p(v_pid article.pid%type,v_level binary_integer) is
cursor c is select * from article where pid = v_pid;
v_preStr varchar2(1024) := '';
begin
for i in 0..v_level loop
v_preStr := v_preStr || '****';
end loop;

for v_article in c loop
    dbms_output.put_line(v_preStr ||v_article.cont);
    if(v_article.isleaf=0) then
       p(v_artile.id,v_levle +1);
    end if;
end loop;
end;

断点 2010-07-24 16:25 发表评论

断点 — Sat, 24 Jul 2010 08:22:00 GMT

--触发�?br /> create table emp2_log
(
uname varchar2(20);
action varchar2(10);
atime date
);

create or replace trigger trig
after insert or delete or update on emp2 for each row
begin
if inserting then
     insert into emp2_log values (USER,'insert',sysdate); --USER关键字，用户�?br /> elsif updating then
     insert into emp2_log values (USER,'update',sysdate);
elsif deleting then
     insert into emp2_log values (USER,'delete',sysdate);
end if;
end;

update emp2 set sal = sal*2 where deptno = 30;
select * from emp2_log;

drop trigger trig;

--直接执行�Ӟ��出现�q�反完整�U�束条�g�Q�已扑ֈ�子记录�?br /> update dept set deptno = 99 where deptno = 10;

--使用下面的，把子表一��h��新�?br /> create or replace trigger trig
after update on dept for each row
begin
update emp set deptno =:NEW.deptno where deptno =:OLD.deptno;
end;

update dept set deptno = 99 where deptno = 10;

select * from emp;
rollback;

断点 2010-07-24 16:22 发表评论

function函数

断点 — Sat, 24 Jul 2010 08:19:00 GMT

--函数
create or replace function sal_tax
   (v_sal number)
   return number
is
begin
if(v_sal < 2000) then
    return 0.10;
elsif(v_sal < 2750) then
    return 0.15;
else
    return 0.20;
end if;
end;

数据库定义的函数money_to_chinese �Q�把数字转换正中文输出�?/span>
create or replace function money_to_chinese(money in VARCHAR2)
   return varchar2 is
     c_money   VARCHAR2(12);
     m_string VARCHAR2(60) := '分角圆拾��C��万拾��C��?;
     n_string VARCHAR2(40) := '壹贰叁肆伍陆柒捌�?;
     b_string VARCHAR2(80);
     n         CHAR;
     len       NUMBER(3);
     i         NUMBER(3);
     tmp       NUMBER(12);
     is_zero   BOOLEAN;
     z_count   NUMBER(3);
     l_money   NUMBER;
     l_sign    VARCHAR2(10);

   BEGIN
     l_money := abs(money);
     IF money < 0 THEN
       l_sign := '�? ;
     ELSE
       l_sign := '';
     END IF;
     tmp      := round(l_money, 2) * 100;
     c_money := rtrim(ltrim(to_char(tmp, '999999999999')));
     len      := length(c_money);
     is_zero := TRUE;
     z_count := 0;
     i        := 0;
     WHILE i < len LOOP
       i := i + 1;
       n := substr(c_money, i, 1);
       IF n = '0' THEN
         IF len - i = 6 OR len - i = 2 OR len = i THEN
           IF is_zero THEN
             b_string := substr(b_string, 1, length(b_string) - 1);
             is_zero   := FALSE;
           END IF;
           IF len - i = 6 THEN
             b_string := b_string || '�?;
           END IF;
           IF len - i = 2 THEN
             b_string := b_string || '�?;
           END IF;
           IF len = i THEN
              IF (len = 1) THEN
                 b_string := '零圆�?;
              ELSE
                 b_string := b_string || '�?;
              END IF;
           END IF;
           z_count := 0;
         ELSE
           IF z_count = 0 THEN
             b_string := b_string || '�?;
             is_zero   := TRUE;
           END IF;
           z_count := z_count + 1;
         END IF;
       ELSE
         b_string := b_string || substr(n_string, to_number(n), 1) ||
                     substr(m_string, len - i + 1, 1);
         z_count   := 0;
         is_zero   := FALSE;
       END IF;
     END LOOP;
     b_string := l_sign || b_string ;
     RETURN b_string;
exception
   --异常处理
    WHEN OTHERS THEN
       RETURN(SQLERRM);
END;

断点 2010-07-24 16:19 发表评论

procedure存储�q�程

断点 — Sat, 24 Jul 2010 08:17:00 GMT

--创徏存储�q�程�Q?br /> create or replace procedure p
is
cursor c is
select * from emp2 for update;
begin
for v_temp in c loop
    if(v_temp.deptno = 10) then
      update emp2 set sal = sal+10 where current of c;
    elsif(v_temp.deptno = 20) then
      update emp2 set sal = sal+20 where current of c;
    else
       update emp2 set sal = sal+50 where current of c;
    end if;
end loop;
commit;
end;

--执行�Q?br /> exec p;

begin
p;
end;

--带参数的存储�q�程�Q�in传入参数�Q�默认�ؓ传入�Q�out传出�?/span>
create or replace procedure p
   (v_a in number,v_b number,v_ret out number,v_temp in out number)
is
begin
if(v_a >v_b) then
    v_ret := v_a;
else
    v_ret := v_b;
end if;
v_temp :=v_temp +1;
end;

declare
v_a number := 3;
v_b number := 4;
v_ret number;
v_temp number := 5;
begin
p(v_a,v_b,v_ret,v_temp);
dbms_output.put_line(v_ret);
dbms_output.put_line(v_temp);
end;

断点 2010-07-24 16:17 发表评论

cursor游标

断点 — Sat, 24 Jul 2010 08:14:00 GMT

--游标
declare
cursor c is
    select * from emp;
v_emp c%rowtype;
begin
open c;
loop
    fetch c into v_emp;
    exit when(c%notfound);
    dbms_output.put_line(v_emp.ename);
end loop;
close c;
end;

declare
cursor c is
    select * from emp;
v_emp emp%rowtype;
begin
open c;
fetch c into v_emp;
    while(c%found) loop
      dbms_output.put_line(v_emp.ename);
      fetch c into v_emp;
      --fetch c into v_emp; ��D��W�一条没有打华ͼ�最后一条打�?遍�?br />       --dbms_output.put_line(v_emp.ename);
end loop;
close c;
end;

declare
cursor c is
    select * from emp;
begin
  for v_emp in c loop
    dbms_output.put_line(v_emp.ename);
end loop;
end;

--带参数的游标
declare
cursor c(v_deptno emp.deptno%type,v_job emp.job%type)
is
    select ename,sal from emp where deptno =v_deptno and job= v_job;
    --v_temp c%rowtype;
begin
for v_temp in c(30,'CLERK') loop --for自动打开游标�?br />     dbms_output.put_line(v_temp.ename);
end loop;
end;

--可更新的游标
declare
cursor c
is
    select * from emp2 for update;
    --v_temp c%rowtype;
begin
for v_temp in c loop
    if(v_temp.sal <2000) then
      update emp2 set sal = sal*2 where current of c;
    elsif(v_temp.sal = 5000) then
      delete from emp2 where current of c;
    end if;
end loop;
commit;
end;

断点 2010-07-24 16:14 发表评论

PL/SQL语句

断点 — Sat, 24 Jul 2010 08:03:00 GMT

PLSql是SQL的补充，PL�q�程语言procedure language�Q�SQL�Q�Structured Query Language�?br /> PLSql 带有分支、��@环的语言�Q�SQL没有分支、��@环的语言�?/span>

set serveroutput on;

-- ��单的PL/SQL语句�?/span>
declare
v_name varchar2(20);
begin
v_name :='myname';
dbms_output.put_line(v_name);
end;
/

--语句块的�l�成
declare
v_num number := 0 ;
begin
v_num := 2/v_num;
dbms_output.put_line(v_num);
exception
when others then
dbms_output.put_line('error');
end;
/

--变量声明的规�?br /> 1、变量名不能够��用保留字�Q�如from、select�{?br /> 2、第一个字�W�必��L��字母
3、变量名最多包�?0个字�W?br /> 4、不要与数据库的表或者列同名
5、每一行只能声明一个变�?/span>

--常用变量�c�d��
1、binary_integer�Q�整敎ͼ�主要用来计数而不是用来表�C�字�D늱��?br /> 2、number�Q�数字类�?br /> 3、char�Q�定长字�W�串
4、varchar2�Q�变长字�W�串
5、date�Q�日�?br /> 6、long�Q�长字符�Ԍ��最�?GB
7、boolean�Q�布��类型，可以取值true、false和null�?/span>

--变量声明
declare
v_temp number(1);
v_count binary_integer :=0;
v_sal number(7,2):= 4000.00;
v_date date:= sysdate;
v_pi constant number(3,2) := 3.14; --constant相当java的final帔R��
v_valid boolean := false;
v_name varchar2(20) not null :='MyName';
begin
dbms_output.put_line('v_temp value:'|| v_temp);
end;

--变量声明�Q��?type属�?br /> declare
v_empno number(4);
v_empno2 emp.empno%type;
v_empno3 v_empno2%type;
begin
dbms_output.put_line('Test');
end;

--��单变量赋�?br /> declare
v_name varchar2(20);
v_sal number(7,2);
v_sal2 number(7,2);
v_valid boolean :=false;
v_date date;
begin
va_name :='MyName';
v_sal :=23.77;
v_sal2 :=23.77;
v_valid:=(v_sal = v_sal2);
v_date:=to_date('1999-08-12 12:23:38','YYYY-MM-DD HH24:MI:SS');
end;

--Table变量�c�d��Q�定义一�U�新的类型，是数�l��?/span>
declare
type type_table_emp_empno is table of emp.empno%type index by binary_integer;
v_empno type_table_emp_empno;
begin
v_empnos(0) := 7369;
v_empnos(2) := 7839;
v_empnos(-1) := 9999;
dbms_output.put_line(v_empnos(-1));
end;

--Record变量�c�d��,�c�M��java的类的概��c�?/span>
declare
type type_record_dept is record
(
    deptno dept.deptno%type,
    dname dept.dname%type,
    loc dept.loc%type
);
v_tmp type_record_dept;
begin
v_tmp.deptno := 50;
v_tmp.dname := 'aaaa';
v_tmp.loc := 'bj';
dbms_output.put_line(v_temp.deptno||''||v_temp.dname);
end;

--使用%rowtype声明Record变量
declare
v_temp dept%rowtype;
begin
v_tmp.deptno := 50;
v_tmp.dname := 'aaaa';
v_tmp.loc := 'bj';
dbms_output.put_line(v_temp.deptno||''||v_temp.dname);
end;

--SQL语句的运用，�q�回数据有且只有一条记录�?br /> declare
v_ename emp.ename%type;
v_sal emp.sal%type;
begin
select ename,sal into v_ename,v_sal from emp where empno = 7369;
dbms_output.put_line(v_ename||''||v_sal);
end;

declare
v_emp emp%rowtype;
begin
select * into v_emp from emp where empno = 7369;
dbms_output.put_line(v_emp.ename);
end;

declare
   v_deptno dept.deptno%type := 50;
   v_dname dept.dname%type := 'aaaa';
   v_loc dept.loc%type := 'bj';
begin
insert into dept2 values (v_deptno,v_dname,v_loc);
commit;
end;

declare
v_deptno emp2.deptno%type := 10;
v_count number ;
begin
--update emp2 set sal = sal/2 where deptno = v_deptno;
--select deptno into v_deptno from emp2 where empno = 7369;
select count(*) into v_count from emp2;
dbms_output.put_line(sql%rowcount||'条记录被影响');
commit;
end;

DDL语句�Q?br /> begin
execute immediate 'create table T(nnn varchar2(20) default ''aaa'')';
end;

--if语句�Q�取�?369的薪��_��如果<1200�Q�则输出'low'�Q�如�?lt;2000则输�?middle'�Q�否�?high'
declare
v_sal emp.sal%type;
begin
select sal into v_sal from emp where empno = 7369;
if(v_sal < 1200) then
    dbms_output.put_line('low');
elsif(v_sal < 2000) then
    dbms_output.put_line('middle');
else
    dbms_output.put_line('high');
end if;
end;

--循环
declare
i binary_integer := 1;
begin
loop
    dbms_output.put_line(i);
    i := i+ 1;
    exit when (i >= 11);
end loop;
end;

declare
j binary_integer := 1;
begin
  while j< 11 loop
    dbms_output.put_line(j);
    j := j+ 1;
end loop;
end;

begin
for k in 1..10 loop
dbms_output.put_line(k);
end loop;

for k in reverse 1..10 loop
dbms_output.put_line(k);
end loop;
end;

--错误处理
declare
v_temp number(4);
begin
select empno into v_temp from emp where deptno = 10;
exception
when too_many_rows then
dbms_output.put_line('太多记录�?);
when others then
dbms_output.put_line('error');
end;

declare
v_temp number(4);
begin
select empno into v_temp from emp where empno = 2222;
exception
when no_data_found then
dbms_output.put_line('没数�?);
end;

create table errorlog
(
id number primary key,
errcode number,
errmsg varchar2(1024),
errdate date
);

create sequence seq_errorlog_id start with 1 increment by 1;

declare
v_deptno dept.deptno%type := 10;
v_errmsg varchar2(1024);
begin
delete from dept where deptno = v_deptno;
commit;
exception
when others then
rollback;
v_errcode := SQLCODE; --关键字，代表出错的代码�?br /> v_errmsg := SQLERRM;
insert into errorlog values (seq_errorlog_id.nextval,v_errcode,v_errmsg,sysdate);
commit;
end;

断点 2010-07-24 16:03 发表评论

数据库设计准则（�W�一、第二、第三范式说明）

断点 — Sun, 18 Jul 2010 02:23:00 GMT

构造数据库必须遵��@一定的规则。在关系数据库中�Q�这�U�规则就是范式�?/span>关系数据库中的关�p�d��L��一定的要求�Q�即满��不同的范式。目前关�p�L��据库有六�U�范式：�W�一范式�Q?NF�Q�、第二范式（2NF�Q�、第三范式（3NF�Q�、第四范式（4NF�Q�、第五范式（5NF�Q�和�W�六范式�Q?NF�Q�。满��x��低要求的�?/span>式是�W�一范式�Q?NF�Q�。在�W�一范式的基��上进一步满��x��多要求的�U�Cؓ�W�二范式�Q?NF�Q�，其余范式以次�c�L��。一般说来，数据库只需满��W�三范式�Q?NF�Q�就行了�?/span>

�W�一范式�Q?NF�Q�：无重复的列�?/span>
所谓第一范式�Q?NF�Q�是指数据库表的每一列都是不可分割的基本数据��，同一列中不能有多�?/span>��|��卛_��体中的某个属性不能有多个值或者不能有重复的属性。如果出现重复的属性，��可能需要定义一个新的实体，新的实体由重复的属性构成，新实体与原实体之间�ؓ一对多关系。在�W�一范式�Q?NF�Q�中表的每一行只包含一个实例的信息。简而言之，�W�一范式��是无重复的列�?br />
数据库表中的字段都是单一属性的�Q�不可再分。这个单一属性由基本�c�d��构成�Q�包括整型、实数、字�W�型、逻辑型、日期型�{��?/span>

说明�Q�在��M��一个关�p�L��据库中，�W�一范式�Q?NF�Q�是对关�p�L��式的基本要求�Q�不满��W�一范式�Q?NF�Q�的数据库就不是关系数据库�?

�W�二范式�Q?NF�Q�：属性完全依赖于主键[消除部分子函��C��赖]�?br />
�W�二范式�Q?NF�Q�是在第一范式�Q?NF�Q�的基础上徏立�v来的�Q�即满��W�二范式�Q?NF�Q�必��d��?/span>��第一范式�Q?NF�Q�。第二范式（2NF�Q�要求数据库表中的每个实例或行必��d��以被惟一地区分。�ؓ�?/span>现区分通常需要�ؓ表加上一个列�Q�以存储各个实例的惟一标识。例如员工信息表中加上了员工�~�号�Q�emp_id�Q�列�Q�因为每个员工的员工�~�号是惟一的，因此每个员工可以被惟一区分。这个惟一属性列被称��Z��关键字或主键、主码�?
�W�二范式�Q?NF�Q�要求实体的属性完全依赖于��d��键字。所谓完全依赖是指不能存在仅依赖�?/span>关键字一部分的属性，如果存在�Q�那么这个属性和��d��键字的这一部分应该分离出来形成一个新的实体，新实体与原实体之间是一对多的关�p�R��ؓ实现区分通常需要�ؓ表加上一个列�Q�以存储各个实例�?/span>惟一标识。简而言之，�W�二范式��是属性完全依赖于主键�?

�W�三范式�Q?NF�Q�：属性不依赖于其它非��d��性[消除传递依赖]�?/span>

满��W�三范式�Q?NF�Q�必��d��满��W�二范式�Q?NF�Q�。简而言之，�W�三范式�Q?NF�Q�要求一个数据库表中不包含已在其它表中已包含的非��d��键字信息。例如，存在一个部门信息表�Q�其中每�?/span>部门有部门编��P��dept_id�Q�、部门名�U�、部门简介等信息。那么在的员工信息表中列出部门编号后��?/span>不能再将部门名称、部门简介等与部门有关的信息再加入员工信息表中。如果不存在部门信息表，�?/span>�Ҏ��W�三范式�Q?NF�Q�也应该构徏它，否则��׃��有大量的数据冗余。简而言之，�W�三范式��是属性不�?/span>赖于其它非主属性�?br /> 所谓传递函��C��赖，指的是如果存�?A → B → C"的决定关�p�，则C传递函��C��赖于A�?/span>

断点 2010-07-18 10:23 发表评论

Sequence序列

断点 — Sat, 17 Jul 2010 14:08:00 GMT

序列�Q�sequence�Q��生一个独一无二的序列，是oracle�Ҏ��的�?/p>

create table article
(
id number,
title varchar2(1024),
cont long
);
insert into article values(seq.nextval,'a','b');

select * from user_sequences; --查询序列

create sequence seq; --创徏序列seq对象
select seq.nextval from dual;
drop sequence seq;

断点 2010-07-17 22:08 发表评论

View视图

断点 — Sat, 17 Jul 2010 03:03:00 GMT

视图�Q�一个虚表，也是一个子查询�Q�是存储在数据字兔R��的一条select语句�?
视图�Q�基于一个表或多个表或视囄��逻辑表，本��n不包含数据，通过它可以对表里面的数据�q�行查询和修改，视图��Z��的表�U�Cؓ��?/span>

视图的优点：
1、对数据库的讉K��Q�可以有选择性的选取数据库里的一部分信息�Q?span style="color: #0000ff">整张表的信息不对外开�?/span>�?.用户通过��单的查询可以从复杂查询中得到�l�果�?br /> 视图的缺点：
如果一个表的结构改了，相应的视囑֦�果用��C��该表的字�D�，也要�q�行修改�Q?span style="color: #0000ff">增加�l�护工作�?/span>�?/span>

��单视图：只从单表里获取数据，不包含函数和数据�l�，可以实现DML操作�?/span>
复杂视图�Q�从多表获取数据�Q�包含函数和数据�l�，不可以DML操作�?br />
视图的创建：
CREATE [OR REPLACE] [FORCE|NOFORCE] VIEW view_name
[(alias[, alias]...)]
AS subquery
[WITH CHECK OPTION [CONSTRAINT constraint]]
[WITH READ ONLY]
其中�Q?br /> OR REPLACE�Q�若所创徏的试囑ַ��l�存在，ORACLE自动重徏该视图；
FORCE�Q�不��基表是否存在ORACLE都会自动创徏该视图；
NOFORCE�Q�只有基表都存在ORACLE才会创徏该视图：
alias�Q��ؓ视图产生的列定义的别名；
subquery�Q�一条完整的SELECT语句�Q�可以在该语句中定义别名�Q?br style="font-family: " /> WITH CHECK OPTION �Q�插入或修改的数据行必须满��视图定义的约束；
WITH READ ONLY �Q�该视图上不能进行�Q何DML操作�?/span>

例如�Q?br />        CREATE OR REPLACE VIEW dept_sum_vw
               (name,minsal,maxsal,avgsal)
       AS SELECT d.dname,min(e.sal),max(e.sal),avg(e.sal)
       FROM    emp e,dept d
       WHERE e.deptno=d.deptno
       GROUP BY d.dname;
查询视图�Q?span style="color: #008000">select * from user_views;
修改视图�Q?span style="color: #008000">通过OR REPLACE 重新创徏同名视图卛_��?/span>
删除视图�Q?span style="color: #008000">DROP VIEW VIEW_NAME;

视图的定义原则：
1.视图的查询可以��用复杂的SELECT语法�Q�包括连�?分组查询和子查询�Q?br /> 2.在没有WITH CHECK OPTION�?READ ONLY 的情况下�Q�查询中不能使用ORDER BY 子句�Q?br /> 3.如果没有为CHECK OPTION�U�束命名�Q�系�l�会自动��Z��命名�Q��Ş式�ؓSYS_Cn;
4.OR REPLACE选项可以不删除原视图便可更改其定义�ƈ重徏�Q�或重新授予对象权限�?br />
视图上的DML操作�Q�应遵��@的原则：
1.��单视囑֏�以执行DML操作�Q?br /> 2.在视囑֌�含GROUP 函数�Q�GROUP BY子句�Q�DISTINCT关键字时不能删除数据行；
3.在视图不出现下列情况时可通过视图修改��数据或插入数据：
   a.视图中包含GROUP 函数�Q�GROUP BY子句�Q�DISTINCT关键字；
   b.使用表达式定义的列；
   c .ROWNUM伪列�?br /> d.��中未在视图中选择的其他列定义为非�I�Z��无默认倹{�?/p>

WITH CHECK OPTION 子句限定�Q?br /> 通过视图执行的INSERTS和UPDATES操作不能创徏该视图检索不到的数据�?/span>�Q�因为它会对插入或修改的数据行执行完整性约束和数据有效性检查�?br /> 例如�Q?br />            CREATE OR REPLACE VIEW vw_emp20
           AS SELECT * FROM emp
           WHERE deptno=20
           WITH CHECK OPTION constraint vw_emp20_ck;
          视图已徏立�?br />             查询�l�果�Q?br />            SELECT empno,ename,job FROM vw_emp20;
          EMPNO                ENAME                JOB
---------------------           --------------          -------------
              7369                 SMITH                CLERK
              7566                 JONES               MANAGER
              7902                 FORD                ANALYST
          修改�Q?br />                 UPDATE vw_emp20
                SET        deptno=20
                WHERE   empno=7902;
           ��生错误：
               UPDATE vw_emp20
                              *
               ERROR 位于�W�一行：
               ORA-01402�Q�视图WITH CHECK OPTION �q�反WHERE 子句

断点 2010-07-17 11:03 发表评论

Index索引

断点 — Sat, 17 Jul 2010 02:54:00 GMT

索引�Q?-像字兔R��面的索引�?br />
表徏立烦引后在插入数据时�Q�一要把数据写入表里�Q�二要把该数据记入烦引里面，因此查询效率高、但插入效率低�?br />
create index idx_stu_email on stu(email,class); --�l�合索引�Q�查询效率高�?br /> drop index idx_stu_email;
select * from user_indexes; -- 查询索引

断点 2010-07-17 10:54 发表评论

Oracle数据字典

断点 — Sat, 17 Jul 2010 02:52:00 GMT

Oracle的数据库对象分�ؓ五种�Q�表�Q�视图，序列�Q�烦引和同义词�?/span>

select * from user_tables -- 当前用户下有多少张表
select * from user_views -- 当前用户下有多少张视�?br /> select * from user_sequences; --查询序列
select * from user_indexes; -- 查询索引

select * from user_constraints -- 当前用户下有多少�U�束
select * from dictionary --数据字典表的�?br />

断点 2010-07-17 10:52 发表评论

断点 — Sat, 17 Jul 2010 01:43:00 GMT

DDL�Q�data definition language�Q�：DDL比DML要多�Q�主要的命��o�?span style="color: #0000ff">CREATE、ALTER、DROP�{�，DDL主要是用在定义或改变表（TABLE�Q�的�l�构�Q�数据类型，表之间的链接和约束等初始化工作上�Q�他们大多在建立表时使用�?br />
数据�c�d��Q�VARCHAR2(50)最�?K(4096字节)、CHAR(1)最�?k、NUMBER(10,6)、NUMBER(6)、DATE�?br /> LONG 变长字符�Ԍ��最大长度达2G�?/span>

�U�束条�g�?个：非空、唯一、主键、外键、check�?br />
create table stu
(
id number(6), --primary key
name varchar2(20) constraint stu_name_nn not null, --stu_name_nn别名
sex number(1),
age number(3),
sdate date,
grade number(2) default 1,
class number(4), --references class(id)
email varchar2(50),
--email varchar2(50) unique --字段�U�约束，不能有重复�?br /> constraint stu_name_email_uni unique(name,email), --表��U�束
constraint stu_id_pk primary key(id), --表��U�束
constraint stu_class_fk foreign key(class) references class(id) --被参考字�D�必��L��主键
);

create table class
(
id number(4) primary key,
name varchar2(20) not null
)

alter table stu add(addr varchar2(100)); --对已存在的表新增字段
alter table stu modify(addr varchar2(150)); --对字�D�修�?br /> alter table stu drop (addr); --删除一个字�D?br /> alter table stu drop constraint stu_class_fk;
delete from class;
drop table class;

断点 2010-07-17 09:43 发表评论

断点 — Sun, 11 Jul 2010 07:43:00 GMT

SQL语言共分为四大类�Q�数据查询语�a�DQL�Q�数据操�U�语�a�DML�Q�数据定义语�a�DDL�Q�数据控制语�a�DCL�?/span>

DML�Q�data manipulation language�Q�：它们是SELECT、UPDATE、INSERT、DELETE�Q�就象它的名字一��P��q?条命令是用来�Ҏ��据库里的数据�q�行操作的语�a��?/p>

conn sys/sys as sysdba;
drop user pcisv6 cascade;
exp --备䆾scott用户下的�?br /> --创徏用户,identified��证相当是密码�Q�quota配额��是分配�I�间�?br /> create user pcisv6 identified by 11 default tablespace core6 quota 10M on corev6
grant create session,create table,create view to pcisv6;   --授权�Q�session是用于登录的
imp --导入scott用户下的�?br />
SELECT�Q?br /> select rownum r,ename from emp;    --rownum行数�Q�目前只能��?lt;�?lt;=, 而没有直�?gt;�?的写法�?br /> select ename, sal     --求薪水最高的�?�?br /> from (select ename, sal from emp order by sal desc)
where rownum <= 5;

--求薪水最高的�?�?0�?br /> select ename,sal,rownum r from emp order by sal desc; --r 排序混�ؕ
select ename,sal,rownum r from (select ename,sal from emp order by sal desc); --此时r序号按新表排�?br /> select ename, sal    -- 此处为结�?br /> from (select ename, sal, rownum r
          from (select ename, sal from emp order by sal desc))
where r >= 6
   and r <= 10;

INSERT�Q?br /> insert into dept values(50,'game','bj');    --整条记录
rollback;
create table dept2 as selet * from emp; --创徏dept2�?br /> insert into dept2(deptno,dname) values(60,'game2');    --有选择的字�D�|��?/span>
insert into dept2 select * from dept;    --插入一个表, 2个表�l�构一�?/span>

UPDATE�Q?br /> update emp2 set sal=sal*12,ename=ename||'-' where deptno=10;

DELETE�Q?br /> delete from dept2 where deptno<25;
rollback;

TRANSACTION�Q?br /> transaction 起始一条dml语句�Q�在commit、rollback时完成�?br /> transaction 在执行dml后，在其后有执行了ddl、dcl�Ӟ��事务自动提交�?br /> 在正帔R��出exit�Ӟ��事务自动提交�?br /> 在非正常退出时�Q�事务回滚�?br />
------------------------------------------------------------
例子�Q?br /> �?个表S�Q�C�Q�SC
S�Q�SNO�Q�SNAME�Q�代表（学号�Q�姓名）
C�Q�CNO�Q�CNAME�Q�CTEACHER�Q�代表（译֏��Q�课名，教师�Q?
SC�Q�SNO�Q�CNO�Q�SCGRADE�Q�代表（学号�Q�课��h��l�）
问题�Q?
1�Q�找出没选过“黎明”老师的所有学生姓名�?
2�Q�列�?门以上（�?门）不及格学生姓名及�q�_��成�W�?
3�Q�即学过1可��E�有学过2可��所有学生的姓名�?
��L��标准SQL语言写出�{�案�Q�方�a�也行�Q�请说明是��用什么方�a��Q��?

1.
select sname froms
join sc on (s.sno = sc.sno)
join c(c.cno = sc.cno)
where c.cteacher <> 'liming';
2.
select sname
where sno in (select sno
                 from sc
                where scgrade < 60
                group by sno
               having count(*) >= 2);
3.
select sname
where sno in (select sno
                 from sc
                where cno = 1
                  and sno in (select sno from sc where cno = 2));

断点 2010-07-11 15:43 发表评论

SQL�l�合查询例子

断点 — Tue, 06 Jul 2010 15:25:00 GMT

select e1.ename,e2.ename from emp e1 join emp e2 on (e1.mgr=e2.empno); --自连接，从e2中取出e1的经理�h�?br /> select ename,dname from emp e left join dept d on (e.deptno=d.deptno);   --左外�q�接
select ename,dname from emp e right outer join dept d on (e.deptno=d.deptno);   --叛_��q�接
select ename,dname from emp e full join dept d on (e.deptno=d.deptno);    --全连�?/p>

--求部门中哪些人的薪水最�?br /> select ename,sal from emp
join (select max(sal) max_sal,deptno from emp group by deptno) t
on (emp.sal = t.max_sal and emp.deptno = t.deptno);

--求部门��^均薪水的�{��
select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal);

--求部门��^均的薪水�{��
select avg(grade) from
(select deptno,ename,grade from emp join salgrade s on (emp.sal between s.losal and s.hisal )) t
group by deptno;

--雇员中有哪些人是�l�理�?br /> select ename from emp where empno in (select distinct mgr from emp);

--不准用组函数�Q�求薪水的最高倹{��采用的是自�q�接�?br /> select distinct sal from emp where sal not in
(select distinct e1.sal from emp e1 join emp e2 on (e1.sal < e2.sal));

--求��^均薪水最高的部门的部门编受��嵌套的�l�函数�?br /> select deptno,avg_sal from
(select avg(sal) avg_sal,deptno from emp group by deptno)
where avg_sal =
(select max(avg(sal)),deptno from emp group by deptno;

--求��^均薪水的�{��最低的部门的部门名�U��?br /> select dname,t1.deptno,grade,avg_sal from
(
   select deptno,grade,avg_sal from
     (select deptno,avg(sal) avg_sal from emp group by deptno) t
     join salgrade s on (t.avg_sal between s.losal and s.hisal)
)
   t1
   join dept on (t1.deptno = dept.deptno)
)
where t1.grade =
(
select min(grade) from
     (select deptno,grade,avg_sal from
  (select deptno,grade,avg(sal) avg_sal from emp group by deptno) t
   join salgrade s on (t.avg_sal between s.losal and s.hisal)
     )
)

--求��^均薪水的�{��最低的部门的部门名�U�。采用视图�?br /> conn sys/sys as sysdba;
grant create table,create view to scott;

create view v$_dept_avg_sal_info as
select deptno,grade,avg_sal from
(select deptno,grade,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal);

select dname,t1.deptno,grade,avg_sal from
v$_dept_avg_sal_info t1
join dept on (t1.deptno = dept.deptno)
)
where t1.grade =
(
select min(grade) from v$_dept_avg_sal_info
)

-- 比普通员工的最高薪水还要高的经理�h名称�?br /> select ename from emp
where empno in (select distinct mgr from emp where mgr is not null)
and sal >
(
select max(sal) from emp where empno not in
(select distinct mgr from emp where mgr is not null)
)

断点 2010-07-06 23:25 发表评论

断点 — Tue, 06 Jul 2010 15:18:00 GMT

--1992�q�sql标准�Q�连接条件和�q��o条�g写在一赗��?/span>
select ename,dname,grade
from emp e,dept d,salgrade s
where e.deptno = d.deptno and e.sal between s.losal and s.hisal and job<>'CLERK';

--1999�q�sql标准,�q�接条�g和过滤条件分开
select ename,dname,grade
from emp e join dept d on (e.deptno = d.deptno)
join salgrade s on (e.sal between s.losal and s.hisal)
where ename not like '_A%';

断点 2010-07-06 23:18 发表评论

常用sql函数

断点 — Wed, 30 Jun 2010 15:38:00 GMT

select chr(65) from dual;
select ascii('A') from dual; --求编�?br /> select ename from emp where lower(ename) like '_a%' -- upper大写
select round(23.652,2) from dual; -- 四舍五入 23.65,round(23.652)�?4
select substr(ename,1,3) from emp; --从第一个开始，��L��?个�?br /> select ename,sal,deptno from emp where length(sal)>3;

select to_char(sal,'$99,999.9999') from emp; --'L00000.0000'千位不够�?
select to_char(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual;

select ename,hiredate from emp where hiredate>to_date('1981-2-20 12:34:56','YYYY-MM-DD HH24:MI:SS');

select sal from emp where sal>to_number('$1,250.00','$9,999.99');

select ename,sal*12 + nvl(comm,0) from emp; --对空值处�?br />

�l�函敎ͼ�
select max(sal) from emp;
select min(sal) from emp;
select avg(sal) from emp;
select sum(sal) from emp;
select count(*) from emp; -- *求出总记录数, count(comm)求出该列不�ؓ�I�的倹{�?br /> select deptno,job,max(sal) from emp group by deptno,job; --按照条�g�l�合分组
select ename from emp where sal =(select max(sal) from emp); --子查�?br />
update Web_Bas_Edr_Rsn set c_rsn_txt=REPLACE(c_rsn_txt,'天��|','北京') where c_rsn_txt like '%天��|%' --扚w��替换

-- having对分�l�进行限�Ӟ��where对单行限�?/span>
select avg(sal) from emp where sal>1000 group by deptno having avg(sal) >1500 order by avg(sal) desc;

断点 2010-06-30 23:38 发表评论

常用sql操作

断点 — Tue, 29 Jun 2010 16:45:00 GMT

sqlplus sys/sys as sysdba;
alert user scott account unlock;
desc emp;
select ename,sal*12 from emp;

select sysdate from dual; --dual为空�?/span>

select ename,sal*12 annual_sal from emp; --别名
--数�?null 为null
select ename||sal from emp; --��g��
select ename||'aaa''bbb' from emp; --�?的拼�?''替换�?
select distinct deptno,job from emp; --��L��2个字�D�值的�l�合

select * from emp where deptno=10 and ename='CLARK';
select ename,sal from emp where sal>1500;
select ename,sal from emp where deptno<>10;
select ename,sal from emp where sal between 800 and 1500; -- sal>=800 and sal<=1500
select ename,sal,comm from emp where comm is null; --is not null
select ename,sal,comm from emp where sal in (800,1500); -- not in (800,1500)

select ename from emp where ename like '_A%' -- %�?个或多个�Q?�?�?br /> select ename from emp where ename like '%\%%' -- 名字含有%�Q�需要\��{义字�W�处�?br /> select ename from emp where ename like '%$%%' escape '$' -- 可以使用$作�ؓ转义字符

select ename,sal,deptno from emp order by deptno asc,ename desc; -- 升序asc�Q�降�?desc

断点 2010-06-30 00:45 发表评论

存储�q�程-1

断点 — Sun, 31 Jan 2010 09:48:00 GMT

需求：对WEB_CUS_CLENT机构为空的进行修改，通过WEB_CUS_CLENT客户�~�码查找投保人WEB_PLY_APPLICANT的申请单��P��通过甌��单号查找web_PLY_BASE查找承保机构�?/span>

CREATE OR REPLACE PROCEDURE V6.P_WEB_CUS_CLINT_DPT
IS

--增量抽取客户信息数据
v_task_start_date          date                    ;
v_task_end_date            date                    ;
v_sql_code                 number       :=0        ;
v_sql_msg                  VARCHAR2(4000) := ''    ; --sql错误信息
V_Cus_Client               Web_Cus_Client%rowtype ;
V_UPD_TM                   date;
V_APP_NO                   varchar2(50);
V_DPT_CDE                  varchar2(50);
V_COUNT                    number(4,0);

cursor CUR_WEB_CUS_ADD is
select *
from Web_Cus_Client
a where a.C_DPT_CDE is null;

BEGIN
SELECT SYSDATE INTO v_task_start_date FROM dual; --��d��开始时间和��d��l�束旉��
SELECT SYSDATE INTO v_task_end_date FROM dual;
v_sql_msg := '对WEB_CUS_CLENT机构为空的进行修�?;

open CUR_WEB_CUS_ADD;
     loop
       fetch CUR_WEB_CUS_ADD into V_Cus_Client;
       exit when CUR_WEB_CUS_ADD% notfound;
       v_sql_msg := V_Cus_Client.c_Clnt_Cde||'对WEB_CUS_CLENT机构为空的进行修�?;
       V_COUNT :=0;
     select count(1) into V_COUNT from WEB_PLY_APPLICANT a where a.C_APP_CDE=V_Cus_Client.c_Clnt_Cde;
     if(V_COUNT>0) then
       select max(T_CRT_TM) into V_UPD_TM from WEB_PLY_APPLICANT a where a.C_APP_CDE=V_Cus_Client.c_Clnt_Cde;
       select max(C_APP_NO) into V_APP_NO from WEB_PLY_APPLICANT a where a.T_CRT_TM=V_UPD_TM and a.C_APP_CDE=V_Cus_Client.c_Clnt_Cde;
       select C_DPT_CDE into V_DPT_CDE from web_PLY_BASE a where a.C_APP_NO=V_APP_NO;
       update WEB_CUS_CLIENT a set a.C_DPT_CDE=V_DPT_CDE where a.C_CLNT_CDE=V_Cus_Client.c_Clnt_Cde;
     end if;
     commit;
   end loop;
close CUR_WEB_CUS_ADD;

--写�Q务日�?br /> v_sql_code    :=0;
v_sql_msg     := 'NORMAL, SUCCESSFUL COMPLETION';
SELECT SYSDATE INTO v_task_end_date FROM dual;
INSERT INTO LOAD_HIS_LOG
   ( SYS
     ,JOBNAME
     ,START_DATE
     ,END_DATE
     ,RUN_DATE
     ,SQL_CODE
     ,SQL_STATE
   )
VALUES
    ('V5_MID'
     ,'P_WEB_CUS_CLINT_DPT'
     ,v_task_start_date
     ,v_task_end_date
     ,to_char((v_task_end_date - v_task_start_date) * 86400)
     ,v_sql_code
     ,v_sql_msg
    );
COMMIT;

EXCEPTION
WHEN OTHERS THEN
    v_sql_code := SQLCODE;
    v_sql_msg := v_sql_msg || ' ' || ' : ' || SQLERRM;
    SELECT SYSDATE INTO v_task_end_date FROM dual; --��d��l�束旉��
    ROLLBACK;
    INSERT INTO LOAD_HIS_LOG
   ( SYS
     ,JOBNAME
     ,START_DATE
     ,END_DATE
     ,RUN_DATE
     ,SQL_CODE
     ,SQL_STATE
   )
VALUES
    ('V5_MID'
     ,'P_WEB_CUS_CLINT_DPT'
     ,v_task_start_date
     ,v_task_end_date
     ,to_char((v_task_end_date - v_task_start_date) * 86400)
     ,v_sql_code
     ,v_sql_msg
    );
COMMIT;
END ;

断点 2010-01-31 17:48 发表评论