ibatis主键生成策略

iBatis的sqlMap配置文件的selectKey元素有个type属性，可以指定pre或者post表示前生成(pre)还是后生成(post)。

Oracle设置

<!-- Oracle SEQUENCE -->
<insert id="insertProduct-ORACLE" parameterClass="com.domain.Product">
<selectKey resultClass="int" keyProperty="id" type="pre">
<![CDATA[SELECT STOCKIDSEQUENCE.NEXTVAL AS ID FROM DUAL]]>
</selectKey>
<![CDATA[insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values(#id#,#description#)]]>
</insert>

<!-- Oracle SEQUENCE -->    
<insert id="insertProduct-ORACLE" parameterClass="com.domain.Product">    
    <selectKey resultClass="int" keyProperty="id" type="pre">    
        <![CDATA[SELECT STOCKIDSEQUENCE.NEXTVAL AS ID FROM DUAL]]>    
    </selectKey>    
    <![CDATA[insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values(#id#,#description#)]]>    
</insert>   

MS SQL Server配置

<!-- Microsoft SQL Server IDENTITY Column 改进-->
<insert id="insertProduct-MS-SQL" parameterClass="com.domain.Product">
<selectKey resultClass="int" keyProperty="id">
<![CDATA[insert into PRODUCT (PRD_DESCRIPTION) values(#description#)
SELECT SCOPE_IDENTITY() AS ID ]]>
</selectKey>
</insert>

<!-- Microsoft SQL Server IDENTITY Column 改进-->    
<insert id="insertProduct-MS-SQL" parameterClass="com.domain.Product">    
    <selectKey resultClass="int" keyProperty="id">    
        <![CDATA[insert into PRODUCT (PRD_DESCRIPTION) values(#description#)  
        SELECT SCOPE_IDENTITY() AS ID ]]>  
    </selectKey>    
</insert>  

MySQL配置

<!-- MySQL Last Insert Id -->
lt;insert id="insertProduct-Mysql" parameterClass="com.domain.Product">
<![CDATA[insert into PRODUCT(PRD_DESCRIPTION) values(#description#)]]>
<selectKey resultClass="int" keyProperty="id">
<![CDATA[SELECT LAST_INSERT_ID() AS ID ]]>
<!-- 该方法LAST_INSERT_ID()与数据库连接绑定，同属统一会话级别，不会发生上述MS SQL Server的函数问题。 -->
</selectKey>
lt;/insert>

 <!-- MySQL Last Insert Id -->  
<insert id="insertProduct-Mysql" parameterClass="com.domain.Product">  
    <![CDATA[insert into PRODUCT(PRD_DESCRIPTION) values(#description#)]]>    
    <selectKey resultClass="int" keyProperty="id">  
        <![CDATA[SELECT LAST_INSERT_ID() AS ID ]]>    
        <!-- 该方法LAST_INSERT_ID()与数据库连接绑定，同属统一会话级别，不会发生上述MS SQL Server的函数问题。 -->  
    </selectKey>  
</insert>  

当然mysql中可以用auto_increment!ms sql中也有identity可以用,这样做是为了兼容其他数据库!