mybatis，mysql批量delete多个记录

1.dao 接口中

Integer delete(List<UserDeviceRela> relas);

2.xml

<delete id="delete" parameterType="java.util.List">
delete from relation where
<foreach collection="list" item="item" index="index"
separator="or"> ( device_id=#{item.deviceId} and username=#{item.username}
)
</foreach>
</delete>