Question

I have table1 with columns ( id, id_user ) and table2 with columns (id, username). The users are registered in table2. So what I want is to insert the table2.id of the new registered users in table1.id_user.

我要问:

INSERT INTO table1 (id_user) SELECT id FROM table2;

但结果是:

例如,我在<代码>表1.id上:

新的用户在表2中登记table1.id looks:

and it repeats all the data every time there is a new registered user. How can I fix this to only add the newly registered user?

Answer 1

INSERT INTO table1  (id_user) 
    SELECT id FROM table2 where id not in (select id_user from table1)

如果您使用非行触发器,你可以自动插入表2中的新用户。

Answer 2

使用<条码> 关键词。委员会在您的案例中做了工作。

 " INSERT INTO table1  (id_user) SELECT max id FROM table2"

友情链接