如何在ibatis中用in语句?

我现在想在ibatis中用in语句,写法如下:

<select id="SELECT-LOWST-USER-ID"
parameterClass="java.lang.String"
resultClass="java.lang.String">
<![CDATA[
select currentOpUserID from(
select a.current_op_User_id as currentOpUserID
from tds_t_event_pool a
where a.current_op_User_id in param#
order by a.last_time
)
where rownum = 1
]]>
</select>

我传进去的参数param: (a,b,c)

返回总是null,不知道怎么弄,指教!!

怎么变成下拉框了?把“<”去掉试试

select id="SELECT-LOWST-USER-ID"
parameterClass="java.lang.String"
resultClass="java.lang.String">
<![CDATA[
select currentOpUserID from(
select a.current_op_User_id as currentOpUserID
from tds_t_event_pool a
where a.current_op_User_id in param#
order by a.last_time
)
where rownum = 1
]]>
</select