三表关联查询、更新

查询语句

select issue.id,issue.area,issue.insert_uid,`user`.school_id,school.`name`,school.area as area1 from issue,user,school where issue.insert_uid=`user`.id and `user`.school_id=school.id

更新语句

UPDATE issue INNER JOIN user ON `issue`.insert_uid and `user`.id INNER JOIN

(SELECT  issue.id as id,issue.insert_uid as uid,`user`.school_id as school_id,school.area as area1 from issue,user,school

where issue.insert_uid=`user`.id and  `user`.school_id=school.id) AS T1

ON issue.insert_uid=T1.uid

SET issue.area=T1.area1