iBATIS selectKey返回主键

IBATIS INSERT/UPDATE 中selectkey,可以返回一个结果,若有两个主键如何返回
例子如下

   
 <insert parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (key1,key2,ziD1) values (#key1#,#key2#,#ziD1#)
      ]]>
      <selectKey resultClass="int" keyProperty="key1">
        <![CDATA[
          SELECT key1 AS key1
        ]]>
      </selectKey>
    </insert>

key2如何返回