剛剛用sequence ，又忘了，呵呵，從網上找了一篇文章，寫的不錯，copy 在這里
1、Create?Sequence?
你首先要有CREATE?SEQUENCE或者CREATE?ANY?SEQUENCE權限，?
CREATE?SEQUENCE?emp_sequence?
????INCREMENT?BY?1??--?每次加幾個?
????START?WITH?1????--?從1開始計數?
????NOMAXVALUE??????--?不設置最大值?
????NOCYCLE?????????--?一直累加，不循環?
????CACHE?10;?
一旦定義了emp_sequence，你就可以用CURRVAL，NEXTVAL?
?CURRVAL=返回?sequence的當前值?
?NEXTVAL=增加sequence的值，然后返回?sequence?值?
比如：?
??emp_sequence.CURRVAL?
??emp_sequence.NEXTVAL?
可以使用sequence的地方：?
-?不包含子查詢、snapshot、VIEW的?SELECT?語句?
-?INSERT語句的子查詢中?
-?NSERT語句的VALUES中?
-?UPDATE?的?SET中???
可以看如下例子：?
INSERT?INTO?emp?VALUES??
(empseq.nextval,?'LEWIS',?'CLERK',7902,?SYSDATE,?1200,?NULL,?20);?
SELECT?empseq.currval?????FROM?DUAL;?
但是要注意的是：?
-?第一次NEXTVAL返回的是初始值；隨后的NEXTVAL會自動增加你定義的INCREMENT?BY值，然后返回增加后的值。CURRVAL?總是返回當前SEQUENCE的值，但是在第一次NEXTVAL初始化之后才能使用CURRVAL，否則會出錯。一次NEXTVAL會增加一次SEQUENCE的值，所以如果你在同一個語句里面使用多個NEXTVAL，其值就是不一樣的。明白？?
-?如果指定CACHE值，ORACLE就可以預先在內存里面放置一些sequence，這樣存取的快些。cache里面的取完后，
oracle自動再取一組到cache。?使用cache或許會跳號，?比如數據庫突然不正常down掉（shutdown?abort),cache中的sequence就會丟失.?所以可以在create?sequence的時候用nocache防止這種情況。?
2、Alter?Sequence?
你或者是該sequence的owner，或者有ALTER?ANY?SEQUENCE?權限才能改動sequence.?可以alter除start至以外的所有sequence參數.如果想要改變start值，必須?drop??sequence?再?re-create?.?
Alter?sequence?的例子?
ALTER?SEQUENCE?emp_sequence?
????INCREMENT?BY?10?
????MAXVALUE?10000?
????CYCLE????--?到10000后從頭開始?
????NOCACHE?;?
影響Sequence的初始化參數：?
SEQUENCE_CACHE_ENTRIES?=設置能同時被cache的sequence數目。??
可以很簡單的Drop?Sequence?
DROP?SEQUENCE?order_seq;?
1 Guidelines for Using Subqueries
?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)
1 Jioning Tables Using Oracle Syntax
Using a join to query data form more than one table
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);
?
1 "'
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
??
1 What Are Group Functions
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;
1 Keyboardd Basics
?1) Ignoring the Keyboard
?Your programm does not need to act on every keyboard message it received,Window handle many keyboard message function itself.
?2)Who's Got thefocus
? Though the keyboard is shared by all the window in the application ,The DispatchMessage send the message to the window procedure associated the window which message is intended.
? The window that receives a particular keyboard event is the window has the input foucs.
? Sometime no window has input foucs,this is the case if all your programs have been minmized,window continue send keyboard to the active window ,but it is send in the deffert form from sending to the input foucs.
? A window procedure can be determine when its window has the input focus by trapping WM_SETFOCUS and WM_KILLFOCUS.
?3) Queues and Synchronization
? As the user presses and releases key on keyborad,Windows and keyboard device driver translate the hardware scan code into formatted message.Howerver the messages are not palced on the application queue right away,Instean Windows store these message in a system message queue .The System message queue is a single message maintained by windows specifically for the prelimary storage of user input from keyboard and the mouse. Window will take the next message from the system message queue and place it on the application message queue only when a window application has finished proecssing the previous user input message.
4) Keystorkes and Character
?The message that an application receives from windows about keyboard events distingush between keystrokes and characters.
?for instance The keysokes has only one key labbed 'A' ,and the character may be 'a' or 'ctr-a' etc.
2 Keystroke Message
?1)Wirtual key Codes
? The virtual key code is stored in the wParam parameter of WM_KEYDOWN,WM_KEYUP,the code identifies the key being pressed or release.
? 2)lParam Information
? the wParam message parameter contain virtual key code and the lparam message parameter contains other information in understanding the keystoke.
? 3) Shift States
? iState = GetKeyState (VK_SHIFT) ;
? iState variable will be negative if the Shift key is donw
? iState = GetKeyState (VK_CAPITAL) ;
? 4)Using Keystroke Messages
???
? 5)
?? case WM_KEYDOWN:
???? switch (wParam)
???? {
???? case VK_HOME:
????????? SendMessage (hwnd, WM_VSCROLL, SB_TOP, 0) ;
????????? break ;
???? case VK_END:
????????? SendMessage (hwnd, WM_VSCROLL, SB_BOTTOM, 0) ;
????????? break ;
???? case VK_PRIOR:
????????? SendMessage (hwnd, WM_VSCROLL, SB_PAGEUP, 0) ;
????????? break ;
3 Character Messages
Message Key or Code
WM_KEYDOWN Virtual key code for `A' (0x41)
WM_CHAR Character code for `a' (0x61)
WM_KEYUP Virtual key code for `A' (0x41)
Message Key or Code
WM_KEYDOWN Virtual key code VK_SHIFT (0x10)
WM_KEYDOWN Virtual key code for `A' (0x41)
WM_CHAR Character code for `A' (0x41)
WM_KEYUP Virtual key code for `A' (0x41)
WM_KEYUP Virtual key code VK_SHIFT (0x10)
Key Character Code Duplicated by ANSI C? Escape
Backspace???? 0x08 Ctrl-H??????????????? \b
Tab?????????? 0x09 Ctrl-I??????????????? \t
Ctrl-Enter??? 0x0A Ctrl-J??????????????? \n
Enter???????? 0x0D Ctrl-M???????????????? \r
Esc 0x1B Ctrl-[
? case WM_CHAR:
???? [other program lines]
???? switch (wParam)
???? {
???? case `\b':????????? // backspace
????????? [other program line
????????? break ;
???? case `\t':????????? // tab
????????? [other program lines]
????????? break ;
???? case `\n':????????? // linefeed
????????? [other program lines]
????????? break ;
???? case `\r':????????? // carriage return
????????? [other program lines]
????????? break ;
???? default:??????????? // character codes
????????? [other program lines]
????????? break ;
???? }
???? return 0 ;
1 An Architectural Overview
? 1)Getting a good feel for messages is an import part of learning how to write programs for windows.
? Windows send a message to your porgram means that Windows calls a function in your program .The parameter of this function describe the message that is being send.The function in your program is know as Window Procedure.
? Windows send a message to window by calling window procedure ,The window procedure do some processing based on the message and return control to Windows.
? More precisely , a Window? is always createdd based on a "window class".The window class identifies the window procedure that precesses messages to the windows.The use of window class allow mutiple window to be based the same window class and hence use the same window procedure.
? 2) Requsteriing the Window Class
?typedef struct
?{
???? UINT??????? style ;
???? WNDPROC???? lpfnWndProc ;
???? int???????? cbClsExtra ;
???? int???????? cbWndExtra ;
???? HINSTANCE?? hInstance ;
???? HICON?????? hIcon ;
???? HCURSOR???? hCursor ;
???? HBRUSH????? hbrBackground ;
???? LPCTSTR???? lpszMenuName ;
???? LPCTSTR???? lpszClassName ;
?}
?if (!RegisterClass (&wndclass))
?{
???? MessageBox (NULL, TEXT ("This program requires Windows NT!"),
???????????????? szAppName, MB_ICONERROR) ;
???? return 0 ;
?}
?2)Creating the Window
? Window class define the general Characteristics of the a window.If you want to create window based on the same window class,you can use CreateWindwo which allow you to specify more detail imformation about the window.
? hwnd = CreateWindow (szAppName,????????????????? // window class name
???????????????????? TEXT ("The Hello Program"), // window caption
???????????????????? WS_OVERLAPPEDWINDOW,??????? // window style
???????????????????? CW_USEDEFAULT,????????????? // initial x position
???????????????????? CW_USEDEFAULT,????????????? // initial y position
???????????????????? CW_USEDEFAULT,????????????? // initial x size
???????????????????? CW_USEDEFAULT,????????????? // initial y size
???????????????????? NULL,?????????????????????? // parent window handle
???????????????????? NULL,?????????????????????? // window menu handle
???????????????????? hInstance,????????????????? // program instance handle
???????????????????? NULL) ;???????????????????? // creation parameters
?3)Displaying the window
?? When thee CreateWindow function return ,windows create a window internal.What it means is that windows allocate a block memory to store the imformation about the window.If you want to show that ,you should call
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;?
?4) The Message Loop
?while (GetMessage (&msg, NULL, 0, 0))
?{
???? TranslateMessage (&msg) ;
???? DispatchMessage (&msg) ;
?}
?typedef struct tagMSG
{
???? HWND?? hwnd ;
???? UINT?? message ;// message identifier
???? WPARAM wParam ;
???? LPARAM lParam ;
???? DWORD? time ; // the time the message is placed on the message queen
???? POINT? pt ; // the mouse coordiante
?}
?typedef struct tagPOINT
?{
???? LONG? x ;
???? LONG? y ;
?}
POINT, * PPOINT;
the message filed of message retrived from the message queen is anyting except WM_QUITm ,GetMessage return a nonzero value
wM_QUIT cause GetMessage reuturn 0.
TranslateMessage (&msg) ;
passing the msg struct back to window for some keysboard translation
DispatchMessage (&msg) ;
pass the msessageback to window .Windwo then send the message to the appropriate window procedure for processing.After window
procedure processing the message ,it return control to the windows,which is still in serving the Dispatchmessage
?5) The Window Procedure
? a The window procedure determined the how the window display on the client area and how the window respose to user input
? b LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam),the four parameter is idential to the first four filed of the message struct.
?6) Processing the Message
?switch (iMsg)
{
case WM_CREATE :
???? [process WM_CREATE message]
???? return 0 ;
?????????
case WM_PAINT :
???? [process WM_PAINT message]
???? return 0 ;
?????????
case WM_DESTROY :
???? [process WM_DESTROY message]
???? return 0 ;
}
return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
when a window procedure process the message ,it should return 0;
?7) The WM_PAINT Message
? WU_PAINT message is extremely import in window.it inform a program when part or all of the window 's client area are invalid and must be redraw or repaint.
?WM_PAINT processing almost always begins with a call to BeginPaint:
? hdc = BeginPaint (hwnd, &ps) ; //return a handle to device context
and ends with a call to EndPaint:
?EndPaint (hwnd, &ps) ;
?8)The WM_DESTROY Message
? PostQuitMessage (0) ;
??
?WNDCLASS, * PWNDCLASS ;
?#include <windows.h>
/* the same as long _stdcall WndPro(long,unsign int,unsign int ,long)*/
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
/*int _stdcall WinMain(long hInstance,long hPrevInstance,char * szComdLine,int iCmdShow)*/
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,???
??????????????????? PSTR szCmdLine, int iCmdShow)
{
???? static TCHAR szAppName[] = TEXT ("HelloWin") ;
???? HWND???????? hwnd ;
???? MSG????????? msg ;
???? WNDCLASS???? wndclass ;
/*
? all window createe based on this window class will completely repaint whenever? horizational window sizd and vertial??
? window size change.
*/
???? wndclass.style???????? = CS_HREDRAW | CS_VREDRAW ;?????????????????
???? wndclass.lpfnWndProc?? = WndProc ; // set the window procedure for the window class
???? wndclass.cbClsExtra??? = 0 ;
???? wndclass.cbWndExtra??? = 0 ;
???? wndclass.hInstance???? = hInstance ; // the handle of this program
???? wndclass.hIcon???????? = LoadIcon (NULL, IDI_APPLICATION) ;
???? wndclass.hCursor?????? = LoadCursor (NULL, IDC_ARROW) ;
???? wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
???? wndclass.lpszMenuName? = NULL ;
???? wndclass.lpszClassName = szAppName ;
???? if (!RegisterClass (&wndclass))
???? {
????????? MessageBox (NULL, TEXT ("This program requires Windows NT!"),
????????????????????? szAppName, MB_ICONERROR) ;
????????? return 0 ;
???? }
???? hwnd = CreateWindow (szAppName,????????????????? // window class name
????????????????????????? TEXT ("The Hello Program"), // window caption
????????????????????????? WS_OVERLAPPEDWINDOW,??????? // window style
????????????????????????? CW_USEDEFAULT,????????????? // initial x position
????????????????????????? CW_USEDEFAULT,????????????? // initial y position
????????????????????????? CW_USEDEFAULT,????????????? // initial x size
????????????????????????? CW_USEDEFAULT,????????????? // initial y size
????????????????????????? NULL,?????????????????????? // parent window handle
????????????????????????? NULL,?????????????????????? // window menu handle
????????????????????????? hInstance,????????????????? // program instance handle
????????????????????????? NULL) ;???????????????????? // creation parameters
????
???? ShowWindow (hwnd, iCmdShow) ;// iCmdShow determine how the window is to be initially displayed on the screen.
???? UpdateWindow (hwnd) ; // cause the client area to paint
????
???? while (GetMessage (&msg, NULL, 0, 0))
???? {
????????? TranslateMessage (&msg) ;
????????? DispatchMessage (&msg) ;
???? }
???? return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
???? HDC???????? hdc ;
???? PAINTSTRUCT ps ;
???? RECT??????? rect ;
????
???? switch (message)
???? {
???? case WM_CREATE:
????????? PlaySound (TEXT ("hellowin.wav"), NULL, SND_FILENAME | SND_ASYNC) ;
????????? return 0 ;
???? case WM_PAINT:
????????? hdc = BeginPaint (hwnd, &ps) ;//return a handle to device context
?????????
????????? GetClientRect (hwnd, &rect) ;// set the struct rect with the dimensions of the client area
?????????
????????? DrawText (hdc, TEXT ("Hello, Windows 98!"), -1, &rect,
??????????????????? DT_SINGLELINE | DT_CENTER | DT_VCENTER) ;
????????? EndPaint (hwnd, &ps) ;
????????? return 0 ;
?????????
???? case WM_DESTROY:
????????? PostQuitMessage (0) ;// insert a WM_QIUT in the message queue.
????????? return 0 ;
???? }
???? return DefWindowProc (hwnd, message, wParam, lParam) ;
}
2 The Window Programming Hurdles
?1)Queue and noqueue message
? queue message are post the message queue and the noqueue message send to the window procdure directly.
????
1 Understand Transaction
? 1) Introduce Spring's transaction manager
? a? JDBC transactions?
???? <bean id="transactionManager" class="org.springframework.jdbc.
????? datasource.DataSourceTransactionManager">
???? <property name="dataSource">
???? <ref bean="dataSource"/>
???? </property>
???? </bean>
?? b Hibernate transactions
???? <bean id="transactionManager" class="org.springframework.
?????? orm.hibernate.HibernateTransactionManager">
???? <property name="sessionFactory">
???? <ref bean="sessionFactory"/>
???? </property>
???? </bean>
2 Programing transaction in Spring
?? One approach to adding transaction to your code is to programmly add transactional boundary using transiationTemplate class.
?? Programming is good when you want complete control over transactional boundary.but you have to use spring specific class.In most case ,your tansactional needs will not require such precise control over transactional boundaries.That is why you will typically choolse to declare transaction support
? public void enrollStudentInCourse() {
??? transactionTemplate.execute(
??? new TransactionCallback() {
????? public Object doInTransaction(TransactionStatus ts) {
??????? try {
????????? // do stuff?? Runs within doInTransaction()
??????? } catch (Exception e) {
????????? ts.setRollbackOnly(); //Calls setRollbackOnly() to roll Calls setRollbackOnly()???????????????????????????????? //to roll back
??????? }
????????? return null;?? //If successful, transaction is committed
????? }
??? }
?? );
?}
?<bean id="transactionTemplate" class="org.springframework.
?????? transaction.support.TransactionTemplate">
? <property name="transactionManager">
??? <ref bean="transactionManager"/>
? </property>
?</bean>
?<bean id="courseService"
??? class="com.springinaction.training.service.CourseServiceImpl">
?<property name=" transactionTemplate">
???? <ref bean=" transactionTemplate"/>
?? </property>
?</bean>
3 Declaring transactions
? Spring's support for declarative transaction management is implementedd through Spirng's? AOP framework.
? <bean id="courseService" class="org.springframework.transaction.
?????? interceptor.TransactionProxyFactoryBean">
? <property name="proxyInterfaces">
??? <list>
????? <value>
??????? com.springinaction.training.service.CourseService??
????? </value>
??? </list>
? </property>
? <property name="target">
?? <ref bean="courseServiceTarget"/>?? //Bean being proxied
? </property>
?<property name="transactionManager">
?? <ref bean="transactionManager"/>?? //Transaction manager
?</property>
?<property name="transactionAttributeSource">
?? <ref bean="attributeSource"/>?? //Transaction attribute source
?</property>
?</bean>
?1) Understanding transaction attributes
? In Spring transaction attribute is a description of how transaction policies should be
applied to a methods
?? a? Propagation behavior
??? Propagation behavior???????????????? What it means
??? PROPAGATION_MANDATORY??????????????? indicate that the method must run within a????????????????????????????????????????????????? transaction.If no transaction is in progress
???????????????????????????????????????? an exception will be thrown
??? PROPAGATION_NESTED
??? PROPAGATION_NEVER??????????????????? indicate that the method can not run withi a??????????????????????????????????????????????? transaction. if a transaction exist an exception??????????????????????????????????????????? will be thrown.
??? PROPAGATIOM_NOT_SUPPORT????????????? Indicates that the method should not run within a?????????????????????????????????????????? transaction. If an existing transaction is????????????????????????????????????????????????? in progress, it will be suspended for the
???????????????????????????????????????? duration of the method.
??? PROPAGATION_REQUIRED???????????????? indicate that the current method must run within a????????????????????????????????????????? transaction.if an existing transaction is in??????????????????????????????????????????????? progress,the ,method will run with the transaction
???????????????????????????????????????? otherwise a new transaction will be started
??? PROPAGATION_REQUIRENEW?????????????? indicates that the current must run within its own
???????????????????????????????????????? transaction.A new transaction is started and an???????????????????????????????????????????? existing transaction will be suspend
??? PROPAGATION_SUPPORT????????????????? indicate the current mehtod does not require a????????????????????????????????????????? transaction.but may run if on is already in progress?????
??? b Isolation levels?????
??? Isolation level??????????????????? What it means
??? ISOLATION_DEFAULT????????????????? Using the defaul isolation level of the underlying????????????????????????????????????????? database
??? ISOLATION_READ_UNCOMMITTED???????? Allows you read change that have not yet been commit
?????????????????????????????????????? May result in dirty read,phantom read,nonrepeatable???????????????????????????????????????? read
??? ISOLATION_READ_COMMITTED?????????? Allows reads from concurrent transactions that have
?????????????????????????????????????? bean committed.Dirty read are prevent.but platform????????????????????????????????????????? and norepeatable reads may still occur.
??? ISOLATIOM_REPEATABLE_READ????????? Multiple read the same field will yield the same??????????????????????????????????????????? result ,unless changed by the transaction?????????????????????????????????????????????????? itself.Dirty reads ,nonrepeatable are all prevented
?????????????????????????????????????? phantom may still occur
??? ISOLATION_SERIALIZABLE???????????? This fully ACID-compliant isolation level ensusme??????????????????????????????????????? that dirty read,unrepeatable read ,phantom read are??????????????????????????????????????? all prevented.And this is the most slowest isolation
?????????????????????????????????????? since it is typically accomplished by doing full??????????????????????????????????????? table lock on the tables in the transaction.
?? c Read-Only
?? If a transaction performs only read operation against the underlying datastore.when a transaction begin ,it only make sense to declare a transaction as read only on mehtods with
propagation behavior which start a new transaction.
?? Furthermore ,if you are Hibernate as persistence mechanism,declaring a transaction as read only will reult in Hibernate flush mode being set to FLUST_NEVER.this tell hibernate to avoid synchroniztion of objects with database.
?? d Transaction timeout
?? Suppose that your transaction becomes unexpectedly long-running transaction.Because transaction may invole locks on the underlying database.Instead of waiting it out ,you can delcare a transaction to automaitically roll back.
?? because timeout clock begin ticking when a transaction start. it only make sense to declare a transaction timeout on methods with propagation behavior that start a new transaction.
? 2) Declaring a simple transaction policy
?? <bean id="myTransactionAttribute"
??? class="org.springframework.transaction.interceptor.
??????????? DefaultTransactionAttribute">
? <property name="propagationBehaviorName">
??? <value>PROPAGATION_REQUIRES_NEW</value>
? </property>
? <property name="isolationLevelName">
??? <value>ISOLATION_REPEATABLE_READ</value>
? </property>
?</bean>
?<bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? MatchAlwaysTransactionAttributeSource">
? <property name="transactionAttribute">
??? <ref bean="myTransactionAttribute"/>
? </property>
?</bean>
4 Declaring transactions by method name
? 1) Using NameMatchTransactionAttributeSource
? The properties property of NameMatchTransactionAttributeSource maps mehtod to a transaction property descriptor. the property descriptor takes the following form:
? Propagation,isolation,readOnly,-Exception,+Exception
?
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
????????? PROPAGATION_REQUIRES_NEW
????? </prop>
??? </props>
? </property>
?</bean>
?2) Specifying the transaction Isolation level
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
???? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ
????? </prop>
??? </props>
? </property>
?</bean>
?3) Using real-only transaction
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="getCompletedCourses">
??????? PROPAGATION_REQUIRED,ISOLATION_REPEATABLE_READ,readOnly
????? </prop>
??? </props>
? </property>
</bean>
?4)Specifying? rollback rules
? You can sepcify that a transaction be rollback on specify checked exception
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ,
??????? -CourseException
??????? </prop>
???? </props>
??? </property>
? </bean>
? Exception can be marked as negative(-) or postive(+)
? Negative exception will trigger the roll back if the exception (or sublclass of it) is thrown.Postive exception on the other hand indicate that the transacton should be commit
even if the exception is thrown
?5)Using wildcard matches
?<bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="get*">
??????? PROPAGATION_SUPPORTS
????? </prop>
??? </props>
? </property>
</bean>
?6 Short-cut name match transaction
?<bean id="courseService" class="org.springframework.transaction.
?????? interceptor.TransactionProxyFactoryBean">
?? <property name="transactionProperties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW
????? </prop>
??? </props>
?? </property>
?</bean>
一 Unicode 簡介
?1 Unicode 是ASCII 擴展，從傳統的7位，擴展位16 位，可以顯示世界上所有語言
ASCII 碼
?????? 0-???? 1-???? 2-???? 3-???? 4-???? 5-???? 6-???? 7-
-0???? NUL??? DLE??? SP???? 0????? @????? P????? `????? p
-1???? SOH??? DC1??? !????? 1????? A????? Q????? a????? q
-2???? STX??? DC2??? "????? 2????? B????? R????? b????? r
-3???? ETX??? DC3??? #????? 3????? C????? S????? c????? s
-4???? EOT??? DC4??? $????? 4????? D????? T????? d????? t
-5???? ENQ??? NAK??? %????? 5????? E????? U????? e????? u
-6???? ACK??? SYN??? &????? 6????? F????? V????? f????? v
-7???? BEL??? ETB??? '????? 7????? G????? W????? g????? w
-8???? BS???? CAN??? (????? 8????? H????? X????? h????? x
-9???? HT???? EM???? )????? 9????? I????? Y????? I????? y
-A???? LF???? SUB??? *????? :????? J????? Z????? j????? z
-B???? VT???? ESC??? +????? ;????? K????? [????? k????? {
-C???? FF???? FS???? ,????? <????? L????? \????? l????? |
-D???? CR???? GS???? -????? =????? M????? ]????? m????? }
-E???? SO???? RS???? .????? >????? N????? ^????? n????? ~
-F???? SI???? US???? /????? ?????? O????? _????? o????? DEL
?2 雙位字符集
DBCS：double-byte character set，最初的128個代碼是ASCII，較高的128個代碼中的某些總是跟隨著第
二個位元組。這兩個位元組一起（稱作首位元組和跟隨位元組）定義一個字元。
?3 Unicode 解決方案
? Unicode是統一的16位元系統，也DBCS 這樣的同時含有一位和兩位的字符集不同，Unicode 可以表示
65536 個字符。
? Unicode 的缺點是，Unicode 使用的空間是ASCII 的兩倍
二 寬字符和c
?1 char
? char c='A';
? 變量c 用一個字節來存儲，用16 進制表示位0x41
? char * p;
? 32 位系統，一次指針變量需要用4個字節表示
? char * p="Hello!";
? 字符串占用7個字節 其中 6個用于保存字符串，1個用于保存中止符號0
? char [10]
? 占用10個字節
? char a[]="Hello!";
? 占用 7個字節
?2 寬字節
? typedef unsigned short whcar_t?? which is define in the window.h?
? 與unsign short 一樣 為16 字節，兩個字節
? wchar_t c='A'?? 0x0041
? wchar_t *p=L"Hello!"? 指針占用 4個字節 而 字符串占用 14 個字節
?3 寬字元程序庫函數
? char * pc = "Hello!" ;
? iLength = strlen (pc) ;
? wchar_t * pw = L"Hello!" ;
? iLength = wcslen (pw) ;
?4 維護單一原始碼
?Microsoft Visual C++包含的TCHAR.H
?如果定義了名為_UNICODE的識別字，并且程式中包含了TCHAR.H表頭檔案，那么_tcslen就定義為wcslen
?#define _tcslen wcslen
?如果沒有定義UNICODE，則_tcslen定義為strlen：
?#define _tcslen strlen
?如果定義了 _UNICODE識別字，那么TCHAR就是wchar_t：
?typedef wchar_t TCHAR ;
?否則，TCHAR就是char：
?typedef char TCHAR ;
?如果沒有定義_UNICODE識別字
?#define __T(x) x
?#define _T（x） __T（x）
?#define _TEXT（x） __T（x）
三 寬字節和windows
? 1 window 頭文件中的類型
? typedef char CHAR ;
? typedef wchar_t WCHAR ；
? typedef CHAR * PCHAR, * LPCH, * PCH, * NPSTR, * LPSTR, * PSTR ;
? typedef CONST CHAR * LPCCH, * PCCH, * LPCSTR, * PCSTR ;
? typedef WCHAR * PWCHAR, * LPWCH, * PWCH, * NWPSTR, * LPWSTR, * PWSTR ;
? typedef CONST WCHAR * LPCWCH, * PCWCH, * LPCWSTR, * PCWSTR ;
? #ifdef? UNICODE??????????????????
? typedef WCHAR TCHAR, * PTCHAR ;
? typedef LPWSTR LPTCH, PTCH, PTSTR, LPTSTR ;
? typedef LPCWSTR LPCTSTR ;
? #else
? typedef char TCHAR, * PTCHAR ;
? typedef LPSTR LPTCH, PTCH, PTSTR, LPTSTR ;
? typedef LPCSTR LPCTSTR ;
? #endif
? 2 Windows 函數調用
? #ifdef UNICODE
? #define MessageBox? MessageBoxW
? #else
? #define MessageBox? MessageBoxA
? #endif
? 3 Windows 的字符函數
? ILength = lstrlen (pString) ;
? pString = lstrcpy (pString1, pString2) ;
? pString = lstrcpyn (pString1, pString2, iCount) ;
? pString = lstrcat (pString1, pString2) ;
? iComp = lstrcmp (pString1, pString2) ;
? iComp = lstrcmpi (pString1, pString2) ;
? 4 在windows 使用printf
?? windows 并不支持printf 但是可以使用sprintf
?? int printf (const char * szFormat, ...) ;
?? printf ("The sum of %i and %i is %i", 5, 3, 5+3) ;
?? int sprintf (char * szBuffer, const char * szFormat, ...) ;
?? char szBuffer [100] ;
?? sprintf (szBuffer, "The sum of %i and %i is %i", 5, 3, 5+3) ;
?? puts (szBuffer) ;
一 Spring DAO philosophy
?1 Understanding Spring's DataAccesssException
?Spring's DAO frameworks donot throw teechnology-specific exceptions such as SQLException
or HibernateeExcepiton.Instead ,all exceptions thrown are subclasses of DataAccessException
?2 You are not forced to handle DataAccessExceptions
?DataAccessException is a RuntimeException,so it si an unchecked exception.Since these are quite often unrecoverable,you are not forced to handle these exception.
? Instead ,you can catch the exception if recovery is possible.since DataAccessException is not only a RuntimeException,but it subclasses Spring's NestedRuntimeException. This menas that the root Exception is alwarys via NestedRuntimeException's getCause() method.
?3 Work with DataSources
? a getting a Datasource from JNDI
?? <bean id="dataSource"
????? class="org.springframework.jndi.JndiObjectFactoryBean">
?? <property name="jndiName">
??? <value>java:comp/env/jdbc/myDatasource</value>
?? </property>
?? </bean>
? b Creating a Datasource connection pool
?? <bean id="dataSource"
????? class="org.apache.commons.dbcp.BasicDataSource">
? <property name="driver">
??? <value>${db.driver}</value>
? </property>
? <property name="url">
??? <value>${db.url}</value>
? </property>
? <property name="username">
??? <value>${db.username}</value>
? </property>
? <property name="password">
??? <value>${db.password}</value>
? </property>
</bean>
?c Using a DataSource while testing
? DriverManagerDataSource dataSource = new DriverManagerDataSource();
? dataSource.setDriverClassName(driver);
? dataSource.setUrl(url);
? dataSource.setUsername(username);
? dataSource.setPassword(password);
?4 Consistent DAO support
? Spring template class handle the invariant part of data access-controling the trancsaction
manage resource,handling exception .Implementation of callback interface define what is specific to your application--creating statement,binding parameter and marshalling result set.
?Spring separates the fixed an vaiant parts of data access process into tow distince classes:
template and callbacks.Template manage the fixed parts of the process while callback are where you fill in the implement details;
?one the top of template-callback desing ,spring framework provide a support class which your own data access subclass it. And the support class already have a property for holding a template.
?二 Integerating Hibernate with Spring
? 1 Managing Hibernate resources
?? you will keep a single instance of SessionFactory throughtout your application
?? <bean id="sessionFactory"class="org.springframework.
?????????? orm.hibernate.LocalSessionFactoryBean">
???? <bean id="sessionFactory" class="org.springframework.
?????? orm.hibernate.LocalSessionFactoryBean">
???? <property name="dataSource">
?????? <ref bean="dataSource"/>
???? </property>
? </bean>
? you also want to manager how hibernate is configured
? <bean id="sessionFactory" class="org.springframework.
?????? orm.hibernate.LocalSessionFactoryBean">
? <property name="hibernateProperties">
??? <props>
????? <prop key="hibernate.dialect">net.sf.hibernate.
?????????? dialect.MySQLDialect</prop>
??? </props>
? </property>
? …
?</bean>
?and the last thing is whick map files is read
? <bean id="sessionFactory" class="org.springframework.
?????? orm.hibernate.LocalSessionFactoryBean">
? <property name="mappingResources">
???? <list>
???? <value>Student.hbm.xml</value>
???? <value>Course.hbm.xml</value>
???? …
?? </list>
? </property>
???? …
? </bean>
?Now? you have fully configured your sessionfactory ,so we need do create an object which we
will access hibernate. As we know, we will use a template class
? <bean id="hibernateTemplate"
????? class="org.springframework.orm.hibernate.HibernateTemplate">
? <property name="sessionFactory">
??? <ref bean="sessionFactory"/>
? </property>
?</bean>
? <bean id="courseDao" class="com.springinaction.
?????? training.dao.hibernate.CourseDaoHibernate">
? <property name="hibernateTemplate">
??? <ref bean="hibernateTemplate"/>
? </property>
?</bean>
?2 Accessing Hibernate through HibernatTemplate
? The template-callback mechanism in Hibernatee is pretty simple.There is the HibernatTmpplate and one callback interface
? public Student getStudent(final Integer id) {
? return (Student) hibernateTemplate.execute(
??? new HibernateCallback() {
????? public Object doInHibernate(Session session)
????????? throws HibernateException {
??????? return session.load(Student.class, id);
????? }
??? });
?
? The HibernateTemplate class provides some convience methods that implicit create a HibernateCallback instance:
? (Student) hibernateTemplate.load(Student.class, id);
?? hibernateTemplate.update(student);
? hibernateTemplate.find("from Student student " +
??????????????????????????????? "where student.lastName = ?",
??????????????????????????????? lastName, Hibernate.STRING);
? 3 Subclassing HibernateDaoSupport
? public class StudentDaoHibernate extends HibernateDaoSupport
??? implements StudentDao {
? …
? }
? getHibernateTemplate()
? getSession()