爲每個記錄返回一個新行

Question

在previous question我問了如何將user_id與每個表中的記錄進行匹配，如何從3個不同的表中返回id。 SQL-的

select 
    (select id from bla_facebook_accts where user_id = user.user_id) as facebook, 
    (select id from bla_linked_in_accts where user_id = user.user_id) as linkedin, 
    (select id from bla_twitter_accts where user_id = user.user_id) as twitter 
from 
    (select 12 user_id) user 

偉大的作品，但我想每個返回是否每個表都有一個記錄返回一個新行的SELECT語句，並返回多行，如果表中有超過每個記錄一個。

Answer 1

在這裏你去。這也將返回信息的源表。

SELECT'facebook' source, id FROM bla_facebook_accts WHERE (user_id = 12) 
UNION 
SELECT 'linkedin' source, id FROM bla_linked_in_accts WHERE (user_id = 12) 
UNION 
SELECT'twitter' source, id FROM bla_twitter_accts WHERE (user_id = 12) 

Answer 2

我相信你想使用UNION結構：

select id from bla_facebook_accts where user_id = 12 
UNION 
select id from bla_linked_in_accts where user_id = 12 
UNION 
select id from bla_twitter_accts where user_id = 12