DELETE FROM cg_department_relations WHERE id IN (
SELECT a.id FROM cg_department_relations AS a LEFT JOIN cg_hospital as
b ON( a.hid = b.hospitalid ) where b.hospitalid is null )
我这样写语法报错
a.id 用CONCAT(GROUP_CONCAT(a.id)) 变成字符串了
子查询出来有多条结果，怎样把查询出来的记录删掉，