iBatis自动生成的主键 (Oracle,MS Sql Server,MySQL)

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 -->
< insert   id = "insertProduct-MS-SQL"   parameterClass = "com.domain.Product" >
    <![CDATA[insert into PRODUCT (PRD_DESCRIPTION) values(#description#) ]]>
    < selectKey   resultClass = "int"   keyProperty = "id"   type = "post" >
        <![CDATA[SELECT @@IDENTITY AS ID ]]>
        <!-- 该方法不安全 应当用SCOPE_IDENTITY() 但这个函数属于域函数，需要在一个语句块中执行。 -->
    </ selectKey >
</ insert >

<!-- Microsoft SQL Server IDENTITY Column --> 
<insert id="insertProduct-MS-SQL" parameterClass="com.domain.Product"> 
    <![CDATA[insert into PRODUCT (PRD_DESCRIPTION) values(#description#) ]]> 
    <selectKey resultClass="int" keyProperty="id" type="post"> 
        <![CDATA[SELECT @@IDENTITY AS ID ]]>
        <!-- 该方法不安全 应当用SCOPE_IDENTITY() 但这个函数属于域函数，需要在一个语句块中执行。 -->
    </selectKey> 
</insert>

上述MS SQL Server配置随是官网提供的配置，但实际上却恰恰隐患重重！按下述配置，确保获得有效主键。

<!-- 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 -->
< 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 >

<!-- 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>

通过以上方式，可以最大程度上确保插入数据的时候获得当前自增主键。

 

 

原文引用地址：http://www.javaeye.com/topic/215571