Question

I have a user_id key that shows up in Table A, Table B, Table C.

Table A

User_id value
1       A
2       B
3       C

Table B

User_id value
1       A
1       B
1       C

Table C

User_id value
1       A
1       B
0       C

tA is unique on User_id. I am trying to get the number of occurrences in Table B and Table C with that user_id in one query.

I tried:

SELECT tA.user_id, (SELECT count(*) FROM tB as countB GROUP BY tA.user_id),(SELECT count(*) FROM tC as countC GROUP BY tA.user_id) FROM tA where tA.user_id='1'

Answer 1

I think this is what you’re trying to do:

select ta.user_id,
  (select count(*) from tb where ta.user_id = tb.user_id) CountB,
  (select count(*) from tc where ta.user_id = tc.user_id) CountC
from ta
where ta.user_id = 1