mysql - 如果 table1 的值为 X，SQL 更新 table2？

Question

IF EXISTS (SELECT * FROM table1 WHERE group_id='8')
UPDATE table2 SET (...) 
WHERE usertype='numbereight'

我究竟做错了什么？我需要根据 group_id 更新用户类型

Answer 1

试试这个：

UPDATE table2 
SET someColumn = 'somevalue'
WHERE EXISTS(SELECT * FROM table1 WHERE group_id='8')
AND usertype='numbereight'

Answer 2

你可以尝试这样的事情：

UPDATE table2
SET (...) 
WHERE usertype='number eight' AND EXIST(SELECT * FROM table1 WHERE group_id='8');

Answer 3

尝试

UPDATE table2 
SET (...) 
WHERE usertype = 'numbereight'
AND exists (select * from table1 where group_id = '8')

Answer 4

您可以加入表格并更新您需要的任何字段

UPDATE t1 JOIN t2 ON t1.id = t2.id
SET
  t2.field = 'whatever'
WHERE
  t1.group_id= '8' AND
  t2.usertype = 'numbereight'