if(u.DEPT_ID is null or u.DEPT_ID= '0',ug.GRID_ID,u.DEPT_ID) as GRID_ID,
u.REGISTER_TIME from epdc_user u
LEFT JOIN ( select * from (select * from epdc_user_grid_relation order by CREATED_TIME)t group by t.USER_ID)ug ON ug.USER_ID = u.ID AND ug.DEL_FLAG = '0'
where u.DEL_FLAG ='0' and u.PARTY_FLAG = '0' AND u.STATE = '1' and (u.IDENTITY_NO is null or u.IDENTITY_NO = '')
)u
WHERE
<choose>
<whentest="gridId != null and gridId > 0">u.GRID_ID = #{gridId}</when>