mysql中You can't specify target table <tbl> for update in FROM clause错误的意思是说,不能先select出同一表中的某些值,再update这个表(在同一语句中)。 例如下面这个sql:
例如:
DELETE FROM jx_test1 WHERE user_id = (SELECT user_id FROM jx_test1 WHERE createtime < '2013-10-01' ORDER BY User_id LIMIT 1)
错误码: 1093
You can't specify target table 'jx_test1' for update in FROM clause
Execution Time : 00:00:00:000
Transfer Time : 00:00:00:000
Total Time : 00:00:00:000
修改为:
DELETE FROM jx_test1 WHERE user_id = (SELECT a.user_id FROM (SELECT user_id FROM jx_test1 WHERE createtime < '2013-10-01' ORDER BY User_id LIMIT 1) a);
也就是说将select出的结果再通过中间表select一遍,这样就规避了错误
SELECT host.ip,host.name AS host_name,SUBSTRING(`db_instance`.`name`,1,LENGTH(`db_instance`.`name`)-14) AS instance_name,db_instance.port FROM `host` JOIN `db_instance` ON host.id=db_instance.hostID WHERE db_instance.name LIKE '%ft%' ORDER BY host.name