mysql - 在主 UPDATE 语句的子查询中指定相同的表

Question

底部的第二个查询出现以下错误。知道为什么吗？

谢谢

错误: 错误号:1093

You can't specify target table 'menus' for update in FROM clause

作品:

INSERT INTO menus
(name, controller, parent)
VALUES
('A', 'B', (SELECT id FROM menus menus_alias WHERE SHA1(menus_alias.id) = '1'))

两者都不起作用:

UPDATE menus SET
parent = (SELECT id FROM menus menus_alias WHERE SHA1(menus_alias.id) = '1')
WHERE SHA1(id) = '5'

UPDATE menus menus_alias SET
menus_alias.parent = (SELECT id FROM menus WHERE SHA1(id) = '1')
WHERE SHA1(menus_alias.id) = '5'

检查了这些:

• > Mysql error 1093 - Can't specify target table for update in FROM clause
• > mysql - cant specify target table for update in from clause
• > Error (1093):You cant update target table for update in FROM Clause
• > ERROR 1093 (HY000): You can't specify target table 'a' for update in FROM clause

还有一些

Answer 1

使用JOIN

UPDATE menus m1 JOIN menus m2
    ON SHA1(m1.id) = '5' AND SHA1(m2.id) = '1'
   SET m1.parent = m2.id