Question

i am trying this query

SELECT round( avg( DATEDIFF( CURRENT_DATE, age ) /365 ) , 1 )
FROM single_user U
INNER JOIN university_has_single_user T 
ON T.single_user_users_id_user = U.users_id_user
where (
SELECT id_university
FROM university
WHERE university = "ISEL"
)
LIMIT 0 , 30

the output will be 26.8 but there is some problem because if i change the name of the university or simply remove the where clause the result is 26.8 again.

the dates are:

1979-06-23
1988-04-23
1988-04-23.

any help? what is the problem?

Answer 1

where (
SELECT id_university
FROM university
WHERE university = "ISEL"
)

should be

where
  exists (
  SELECT id_university
  FROM university x
  WHERE x.university = "ISEL" AND
    x.universityid = t.universityid
  )

Well, I guess. It’s not exactly clear to me wat your table structure is, and what you’re trying to achieve, but it seems to me that you want to get that number for a given university, passing its name to the query.

If I’m wrong there, please post your table structure and actual goal.