Please tell me the mysql query
I have say 5 tables,
user , t1, t2, t3, t4
user
has a field called id
.
t1
to t4
all have a corresponding field called user_id
, and a field called verification
.
No开发者_开发问答w I need to distinctly(or uniquely) select the user
from user table
, whose id
exists at least once in at least one table among t1
to t4
,and where the verification
field is true
.
From you detail description it looks that you are near solution. The EXISTS and OR need to be used (assuming that TRUE replaced with 1):
SELECT id FROM User u WHERE
EXISTS(SELECT 1 FROM t1 WHERE u.id = t1.user_id AND t1.verification =1)
OR EXISTS(SELECT 1 FROM t2 WHERE u.id = t2.user_id AND t2.verification =1 )
OR EXISTS(SELECT 1 FROM t3 WHERE u.id = t3.user_id AND t3.verification =1 )
OR EXISTS(SELECT 1 FROM t4 WHERE u.id = t4.user_id AND t4.verification =1 )
Tedious rather than difficult:
SELECT id FROM User JOIN t1 ON user.id = t1.user_id WHERE verification = TRUE
UNION
SELECT id FROM User JOIN t2 ON user.id = t2.user_id WHERE verification = TRUE
UNION
SELECT id FROM User JOIN t3 ON user.id = t3.user_id WHERE verification = TRUE
UNION
SELECT id FROM User JOIN t4 ON user.id = t4.user_id WHERE verification = TRUE
I'd use a UNION
set on the t1
-t4
tables to get the user_id
in those, and use that result for a IN()
clause on the user
table, like this:
SELECT * FROM user
WHERE id IN (SELECT user_id FROM t1 WHERE verification = TRUE
UNION
SELECT user_id FROM t2 WHERE verification = TRUE
UNION
SELECT user_id FROM t3 WHERE verification = TRUE
UNION
SELECT user_id FROM t4 WHERE verification = TRUE)'
Just by the nature of how IN()
works, you get distinct user
table results as well.
Try this:
select
distinct u.user
from
user u
where
exists (
(select user_id from t1 where t1.user_id = u.id and t1.verification = true)
OR (select user_id from t2 where t2.user_id = u.id and t2.verification = true)
OR (select user_id from t3 where t3.user_id = u.id and t3.verification = true)
OR (select user_id from t4 where t4.user_id = u.id and t4.verification = true)
)
精彩评论