当你希望更新一批值,且值是通过select条件查询出来时,下面这个错误应该不陌生
You can’t specify target table ‘x’ for update in FROM clause。
错误示范 1: A B 有关联同一个key_id , 根据 B表符合条件 -> 更新A表val值。
UPDATE A a SET a.val = 2 WHERE a.id IN ( SELECT a.id FROM A LEFT JOIN B ON b.key_id = a.key_id WHERE b.satisfy = 1)
解决思路 1: 使用 INNER JOIN (最简洁)
UPDATE A a INNET JOIN B b ON b.key_id = a.key_id SET a.val = 2 WHERE b.satisfy = 1
解决思路 2:
UPDATE A a, (SELECT A.id from A LEFT JOIN B ON B.key_id= A.key_id WHERE B.satisfy = 1) b SET a.val = 2 WHERE a.id = b.id