急！！在ibatis里怎么写union！

SQL code

SELECT  origin FROM game_user  WHERE plat_name='gamedp'  AND game_name='dc2' AND area_name='一服'UNIONSELECT  origin FROM game_user  WHERE plat_name='gamedp'  AND game_name='dc2' AND area_name='二服'UNIONSELECT  origin FROM game_user  WHERE plat_name='gamedp'  AND game_name='dc2' AND area_name='s1'

java里有个数组a[]={“一服”，“二服”，“s1”}

ibatis里的配置

XML code

<select id="queryOrigin"  parameterType="java.lang.String" resultType="com.aiyounet.gas.service.bean.GameUser"> <foreach collection="array"  item="areaName"  open="(" separator="," close=")">         SELECT  DISTINCT  origin AS origin,id AS id FROM game_user  WHERE plat_name=#{platName}  AND game_name=#{gameName}  AND area_name=#{areaName}         <if test=" array.length >1 ">             UNION        </if> </foreach></select>这样写可以不？

[解决办法]
同一个表里，用area_name in ('一服','二服','s1')就可以了
不同表才有union
[解决办法]
<select id="queryOrigin" parameterType="java.lang.String" resultType="com.aiyounet.gas.service.bean.GameUser">
SELECT DISTINCT origin AS origin,id AS id
FROM game_user
WHERE plat_name=#{platName}
AND game_name=#{gameName}
<if test="areaName！=null ">
AND
area_name in
<foreach collection="array" item="areaName" open="(" separator="," close=")">
</foreach>
</if>
</select>