mybatis的insert语句插入数据时的返回值的实现

<insert id="add" parameterClass="xxx">
    insert into A(a, b, c, d)
    VALUE
    (#a#, #b#, #c#, #d#)
</insert> 

<insert id="add" parameterClass="xxx">
    insert into A(a, b, c, d)
    VALUE
    (#a#, #b#, #c#, #d#)
    <selectKey resultClass="java.lang.Integer" keyProperty="id" >
      SELECT @@IDENTITY AS ID
    </selectKey>
</insert>