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junky — Thu, 12 Jul 2007 07:44:00 GMT

一使用外联�?/strong>

　　以前在Oracle中用=(+)�?+)=来进行左外联接和叛_��联接�Q�后来用SQL Server时用*=�?*�q�行外连接左外联接和叛_��联接�Q?br>现在军_��用SQL-92的标准方法：(x��)[OUTER] JOIN�Q�OUTER是可以省略的�?/p>
　　LEFT OUTER JOIN �?nbsp;LEFT JOIN        表示左外联接

　　RIGHT OUTER JOIN �?nbsp;RIGHT JOIN   表示左外联接

　　FULL OUTER JOIN �?nbsp;FULL JOIN        表示左外联接

　　外联接的意思不用多��_(d��)��我们都懂�Q�但是JOIN到底怎么用呢�Q�没有找到很好的资料�Q�只能从例子中学�?f��n)�?ji��n)�Q?/p>
　　1、这个例子也许没有实际意义，只是��Z��(ji��n)说明问题�Q?/p>

CREATE TABLE orders(order_id int, firm_id int, p_id int) CREATE TABLE firms (firm_id int, f_name int) CREATE TABLE products(p_id int, p_name int) select a.order_id, b.f_name, c.p_name from orders a left join firms b on a.firm_id = b.firm_id left join products c on a.p_id = c.p_id

　　说明�Q�orders表是主表�Q�先和从表firms�q�行左联接，再和从表products�q�行左联接�?/p>
　　判断是外联接中的主表�q�是从表主要看from从句中各个表在LEFT JOIN或RIGHT JOIN两边的位�|�：(x��)LEFT JOIN左边的表是主表，RIGHT JOIN双��的表是主表；

　　ON表达�?ji��n)两个表�q�接的条�Ӟ��一般外联接是等��D��接，不等��D��接意义不大；

　　在多个表的连接中�Q�一个表既可以做主表又同时可以做从表�Q��ؓ(f��)�?ji��n)说明这个问题，我们修改以上SQL为：(x��)

select a.order_id, b.f_name, c.p_name from orders a left join firms b on a.firm_id = b.firm_id right join products c on a.order_id = c.p_id

　　�q�个SQL没有什么意义，但从中可以看出a表既是b的主表又是c的从表；到底怎么用，�q�是要根据实际情冉|��军_��是左联接�q�是双��接；

　　那天�Q�看��C��(ji��n)�q�样一个例子：(x��)

create table tab1 (c1 int, c2 int, c3 int) create table tab2 (c1 int, c2 int, c3 int) create table tab3 (c1 int, c2 int, c3 int) create table tab4 (c1 int, c2 int, c3 int) SELECT * FROM tab1 LEFT OUTER JOIN tab2 ON tab1.c3 = tab2.c3 left OUTER JOIN tab3 right OUTER JOIN tab4 ON tab3.c1 = tab4.c1 ON tab2.c3 = tab4.c3

　　�q�种用法�q�真��见�Q�具体怎么个意思，�q�在理解�?..我把它改写成�Q?/p>

SELECT * FROM tab1 left JOIN tab2 ON tab1.c3 = tab2.c3 LEFT OUTER JOIN tab4 ON tab2.c3 = tab4.c3 RIGHT OUTER JOIN tab3  ON tab3.c1 = tab4.c1

　　也许它们是一个意思。我发现加个括号�Q�看的更清楚一些（它是个嵌套）(j��)

SELECT * FROM tab1 LEFT OUTER JOIN tab2 ON tab1.c3 = tab2.c3 left OUTER JOIN (tab3 right OUTER JOIN tab4 ON tab3.c1 = tab4.c1) ON tab2.c3 = tab4.c3

　　�?nbsp;外联接中 "ON + AND" �?nbsp;"ON + WHERE" 的区�?/strong>

　　1、on条�g是外联接时在生成临时表时使用的联�l�条�Ӟ��不论从表是确定��D��是NULL�Q�主表所有的值都�?x��)出玎ͼ?/p>
　　如果再加上and条�g�Q?nbsp;如果and条�g引用的是主表的列�Q�则对结果毫无媄(ji��ng)响，主表的所有纪录依然会(x��)全部出现�Q�如果and条�g引用的是从表的列�Q�则不符合条件的从表�U�录昄��NULL�Q?/p>
　　2、where条�g是在临时表生成后�Q�再对��(f��)时表�q�行�q��o(h��)的条件。��(f��)时表中的所有纪录都受媄(ji��ng)响，不符合条件的�U�录被过滤出�l�果集；

　　3、示例：(x��)

select a.module_id, a.name, b.module_name from fb_autocoding a left join fb_app_module b on a.module_id = b.module_id and b.module_internal_label <> 'LO'; select a.module_id, a.name, b.module_name from fb_autocoding a left join fb_app_module b on a.module_id = b.module_id where b.module_internal_label <> 'LO';

　　�?nbsp;其他Join�q�算

　　merge join�Q�在处理其他联结之前�Q�先把相关两个表联结在一��P��

　　hash join�Q�把一个表join到已�l�被执行�q�join的结果上�Q?/p>
　　用括��h��变join的顺序：(x��)

select catalog.item, catalog.item_color, product.item, color.color_name from catalog full outer join (product cross join color) on catalog.item = product.item and catalog.item_color = color.color_name;

1

junky 2007-07-12 15:44 发表评论

junky — Wed, 11 Jul 2007 05:54:00 GMT
JDBC3 中可以直接获取当前插入记录的 ID ��|��具体的调用方式如下：(x��)

Statement stmt = conn.createStatement();
stmt.executeUpdate("INSERT INTO authors (first_name, last_name) values
(′George′, ′Orwell′)", Statement.RETURN_GENERATED_KEYS);
ResultSet rs = stmt.getGeneratedKeys();
if ( rs.next() ) ...{
    int key = rs.getInt();
}

�׃��实际与数据库交互采用的是 JdbcTemplate�Q�因而需要找到它对这�U�方式的支持。经�q�实际的查看 Spring �?API 发现其本�w�提供相应的�Ҏ(gu��)��支持�Q�经�q�多�ơ的实验后得到如下的实现�Ҏ(gu��)��Q?br>

private void insert(final Profile profile)...{
    final String _save = "insert into Newsletter_Profile (user_id, publication_id, last_update) values (?, ?, getdate())";
    JdbcTemplate template = this.getJdbcTemplate();
    KeyHolder keyHolder = new GeneratedKeyHolder();
    template.update(new PreparedStatementCreator() ...{
        public PreparedStatement createPreparedStatement(Connection con)
         throws SQLException ...{
                        int i = 0;
                        PreparedStatement ps = con.prepareStatement(_save,
             Statement.RETURN_GENERATED_KEYS);
                        ps.setInt(++i, profile.getCustomerId().intValue());
                        ps.setInt(++i, profile.getPublication().getId());
                        return ps;
                  }
            }, keyHolder);
            profile.setId(keyHolder.getKey().intValue());
      }

特别需要注意的地方�?span id=_42_848_Open_Text>Statement.RETURN_GENERATED_KEYS�Q�在使用MS SQL Server 2005 提供�?JDBC Driver 中上面的部分是必��ȝ��。之所以这么说是因�?google 出来的所有资料都是没有该部分的，甚至 Spring 自��n�?document 中也是没有该参数的。我现在不知道那些代码是否能够真正的获取�?Key�Q�但是现在我 suppose 它们是可�?run 的�?br>
如果没有加入 Statement.RETURN_GENERATED_KEYS �Q�在实际�q�行数据库操作时�?x��)出现如下的异常�Q?br>PreparedStatementCallback; uncategorized SQLException for SQL []; SQL state [null]; error code [0]; The statement must be executed before any results can be obtained.; nested exception is com.microsoft.sqlserver.jdbc.SQLServerException: The statement must be executed before any results can be obtained.
caused by : com.microsoft.sqlserver.jdbc.SQLServerException: The statement must be executed before any results can be obtained.
org.springframework.jdbc.UncategorizedSQLException: PreparedStatementCallback; uncategorized SQLException for SQL []; SQL state [null]; error code [0]; The statement must be executed before any results can be obtained.; nested exception is com.microsoft.sqlserver.jdbc.SQLServerException: The statement must be executed before any results can be obtained.
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The statement must be executed before any results can be obtained.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.getGeneratedKeys(Unknown Source)
at weblogic.jdbc.wrapper.PreparedStatement_com_microsoft_sqlserver_jdbc_SQLServerPreparedStatement.getGeneratedKeys(Unknown Source)
at org.springframework.jdbc.core.JdbcTemplate$3.doInPreparedStatement(JdbcTemplate.java:772)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:527)
at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:767)
at com.fdc.reports20.dao.NewsletterDAO.insert(NewsletterDAO.java:179)
at com.fdc.reports20.dao.NewsletterDAO.save(NewsletterDAO.java:153)
at com.fdc.reports20.dao.NewsletterDAO.update(NewsletterDAO.java:138)
at com.fdc.reports20.business.service.user.AlertServiceImpl.updateNewsletter(AlertServiceImpl.java:146)
at com.fdc.reports20.business.service.user.AlertServiceImpl$$FastClassByCGLIB$$52b80fbc.invoke()
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:674)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:154)
at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:52)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:53)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:107)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:615)
at com.fdc.reports20.business.service.user.AlertServiceImpl$$EnhancerByCGLIB$$a12ee5d8.updateNewsletter()
at com.fdc.reports20.web.delegate.AlertBD.updateNewsletter(AlertBD.java:78)
at com.fdc.reports20.web.jpf.um.workbench.WorkBenchController.editPublicationEmails(WorkBenchController.java:149)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

junky 2007-07-11 13:54 发表评论

前触发器和后触发器简�?downmoon)

junky — Tue, 19 Jun 2007 01:35:00 GMT

前触发器和后触发器简�?downmoon)

    触发器是一�U�特�D�的存储�q�程。当Insert Update 或者Delete 语句修改表中一个或者多个行时执行触发器。因为SQL Server 对特定表上的每一个指定操作调用一个触发器�Q�所以可以��用触发器扩展SQL Sever 的内�|�完整性和数据操纵功能.
    注意:不像Delete 语句�Q�Trancate Table 语句不激�z�触发器�Q�W(xu��)rite Text 语句也不�Ȁ�z�触发器�?/span>
    在SQL Sever 2000 中支持两�U�类型的触发器，前触发器(Instead Of Trigger)和后触发�?After Trigger)。前触发器就是在语句执行之前�Ȁ�z�触发器�Q�而后触发器就是在语句执行之后�Ȁ�z�触发器。可以通过FOR 子句来选择使用何种触发器�?br>    当�ؓ(f��)每一�U�操作创��Z��个触发器�Ӟ��可以为所有三�U�操作创��Z��个触发器�Q��ƈ且��用相应的�~�程技术处理每一�U�操作。下面的�C�Z��在For 子句中列��Z��(ji��n)三种语句�c�d��qӞ��且��用条件语句将相应的跟�t�值插入到CustUpdLog 表中�?br>

Create Trigger TrackCustomerUpdates
On AppDta.dbo.Customer
For Insert,Update,Delete
As
Declare @InsertedCount Int
Declare @DeletedCount Int
Set @InsertedCount=(Select Count(*)From inserted)
Set @DeletedCount=(Select Count(*)From deleted)
If ( @InsertedCount>0)Begin
Insert Into AppDta.dbo.CustUpdLog
( CustID,
Action,
UpdUser,
UpdDateTime)
Select CustId,
Case
When( @DeletedCount>0)Then
'Update'
Else 'Insert'
End,
Current_User,
Current_TimeStamp
From inserted
End
Else If(@DeletedCount>0)Begin
Insert Into AppDta.dbo.CustUpdLog
( CustId,
Action,
UpdUser,
UpdDateTime)
select CustId,
'Delete',
Current_User,
Current_TimeStamp
From deleted
End

    正如本例所�C�，无论何时Insert 或者Update 语句影响一个或者多行时�Q�inserted 临时表都有记录行。无��Z��时Delete 或者Update 语句影响一个或者多行时�Q�deleted 临时表都有记录行。对于一个Update 语句�Q�deleted 临时表有旧行�Q�inserted 临时表有新行。这个示例还反映�?ji��n)触发器的另一个重要方面：(x��)对于某个表的Update 或者Delete 操作�Q�即使该语句没有影响到行�Q�也�Ȁ�z�触发器 (也就是说没有满��Where 子句的行)�?触发器的存储�q�程应该预测�q�种可能性�?/span>

    不仅可以��Z��个表创徏多个触发器，而且�q�可以�ؓ(f��)一个表的同一个SQL 语句(例如Update 语句)创徏多个后触发器�Q�不能�ؓ(f��)同一个SQL 语句创徏多个前触发器。每一个新的Create Trigger 语句增加触发器到那些指定表和语句已有的触发器中。对于所创徏的多个触发器�Q�可以用�pȝ��存储�q�程sp_settriggerorder 来指定第一个被�Ȁ�zȝ��触发器和最后一个被�Ȁ�zȝ��触发器，而对于其他的触发器，则不能指定其�Ȁ�z�顺序，只能��q��l�决定。这�U�触发器的特征不�?x��)引起�Q何特�D�的问题。因为��L��可以实现各种动作作�ؓ(f��)正常的存储过�E�，�q�且按照要求的顺序从一个触发器中调用它们�?br>
    ��管触发器是一�U�存储过�E�，但是不能使用Execute 语句调用�?/span>�Q�如果有希望�׃�n触发器和正常的存储过�E�的�~�码�Q�那么只需把共享代码放在存储过�E�中�Q�从触发器中调用它。如果一个触发器修改一个表�Q�那么这些修改可能会(x��)�Ȁ�z�d��一个触发器�Q�或者本�w�。在默认情况下，SQL Sever 允许�q�种嵌套的触发器调用深度�?2层。虽然我们徏议允许嵌套的和叠代的触发器，但是可以使用�pȝ��存储�q�程��止�q�么做。下面的语句在指定的数据库上防止叠代触发器：(x��)
sp_dboption AppDta,`recursive triggers',`false'
    ��Z��(ji��n)在所有数据库中防止嵌套触发器调用(包括叠代调用)�Q�可以��用下面的语句�Q?br>sp_configure `nested triggers',0

    前面以后触发器�ؓ(f��)例介�l�了(ji��n)触发器的基本内容�Q�下面再介绍一下前触发器的不同之处�?span style="COLOR: rgb(255,0,0)">要创��Z��个前触发器必��ȝ��Instead Of 昑ּ�声明�Q�如下面的例子：(x��)

create Trigger TrackCustomerUpdates
On AppDta.dbo.Customer
Instead Of Update
As
Insert Into AppDta.dbo.CustUpdLog
(CustId,
Action,
UpdUser,
UpdDateTime)
Select CustId,
‘Update’,
Current_User,
Current_TimeStamp
From inserted

    与后触发器不同的是：(x��)前触发器既可以在表又可以在视图上创徏�Q�但一条语句只能创��Z��个前触发器，因此�Q�前触发器不存在�Ȁ�z�顺序问�?br>

触发器应用�D例：(x��)从当前数据库服务器的Shop表Insert操作同步到另一台服务器的Shop�?br>

CREATE TRIGGER Trigger_SynShopForInsert1
ON dbo.Shop
FOR INSERT
AS
  insert into OtherServer.dbo.shop
(
lngShopID,strShopCode,strName,strShopName,strDescription,lngIndex
)
select  lngShopID,strShopCode,strName,strShopName,strDescription,lngIndex
from shop where lngShopID in (select lngshopid from inserted)

或者：(x��)

CREATE TRIGGER Trigger_SynShopForInsert2
ON dbo.Shop
FOR INSERT
AS
  insert into OtherServer.dbo.shop
(
lngShopID,strShopCode,strName,strShopName,strDescription,lngIndex
)
select  lngShopID,strShopCode,strName,strShopName,strDescription,lngIndex
from  inserted

junky 2007-06-19 09:35 发表评论

�q�接SQL Server时报的异�怹�处理步骤

junky — Fri, 22 Dec 2006 01:06:00 GMT
1. [SQLServer 2000 Driver for JDBC]Error establishing socket.

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See (t��ng)com.borland.dx.dataset.DataSetException (t��ng)error (t��ng)code: (t��ng) (t��ng)BASE+66 (t��ng)
solaris (t��ng)
com.borland.dx.dataset.DataSetException: (t��ng)[Microsoft][SQLServer (t��ng)2000 (t��ng)Driver (t��ng)for (t��ng)JDBC]Error (t��ng)establishing (t��ng)socket. (t��ng)
(t��ng)
(t��ng) (t��ng) (t��ng) (t��ng) (t��ng) (t��ng) (t��ng) (t��ng)at (t��ng)com.borland.dx.dataset.DataSetException.a(Unknown (t��ng)Source) (t��ng)
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Chained (t��ng)exception: (t��ng)
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是什么原因啊�Q? (t��ng)
--------------------------------------------------------------- (t��ng)
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1、下载Microsoft (t��ng)SQL (t��ng)Server (t��ng)2000 (t��ng)Service (t��ng)Pack (t��ng)3a�q�安装，SQL请选用混和安装模式�Q�！�Q? (t��ng)
http://www.microsoft.com/downloads/details.aspx?FamilyId=90DCD52C-0488-4E46-AFBF-ACACE5369FA3&displaylang=zh-cn (t��ng) (t��ng)
(t��ng) (t��ng) 解压�~�sp3的升�U�包�?�q�要点击setup安装.才能成功升��到sp3 (t��ng) (t��ng)

2、下载SQL (t��ng)Server (t��ng)2000 (t��ng)Driver (t��ng)for (t��ng)JDBC (t��ng)Service (t��ng)Pack (t��ng)3 (t��ng)
http://www.microsoft.com/downloads/details.aspx?FamilyId=07287B11-0502-461A-B138-2AA54BFDC03A&displaylang=en (t��ng)
(t��ng)
3、运行时关闭防火�?br />

junky 2006-12-22 09:06 发表评论