ibatis selecyKey 返回联合主键

flights表有联合主键
flightNumber,inFlag,schDate

<resultMap id="get-flights-result" class="flights"
		groupBy="flightNumber,inFlag,schDate">
		<result property="flightNumber" column="FLIGHTNUMBER" jdbcType="varchar"
			javaType="java.lang.String" />
		<result property="inFlag" column="INFLAG" jdbcType="character"
			javaType="java.lang.String" />
		<result property="schDate" column="SCHDATE" jdbcType="timestamp"
			javaType="java.sql.Timestamp" /></resultMap>

当我插入一条新记录的时候怎么利用selectKey来取得这个刚插入的数据呢?

<insert id="insertFlights" parameterMap="flights-key-param">
		<![CDATA[
		insert into flights (flightNumber,inFlag,schDate) values (?,?,?)
		]]>
		<selectKey keyProperty="" resultClass="" type="">
		<![CDATA[
		
		]]>
		</selectKey>
	</insert>

数据库是db2,系统表是sysibm.sysdummy1(类似oracle dual)