Question

I have a MySQL-Database where I run certain Stored Procedures.

In one of them, I want to sum up the amount a certain user has to pay, the amount he already payed and return all the users, where the amount to be payed isn’t equal the amount paid. I came up with the following (simplyfied) query:

SELECT userId, SUM(costs) as sum_costs, 
  (SELECT SUM(payed)
   FROM payments p WHERE ta.userId=p.userId) as sum_payed
FROM ta 
GROUP BY ta.userId
ORDER BY ta.userId;

This gives me the sum of the costs and the payment for each user. But I do not know, how I can select only the users, where costs and payment are not equal.

WHERE sum_costs != sum_payed 

doesn’t work, because mysql doesn’t know the column ‘sum_costs’ in the WHERE-clause.

Any idea, how to get the selection to work?

Answer 1

SELECT * FROM 
(
SELECT userId, SUM(costs) as sum_costs, 
(SELECT SUM(payed)
FROM payments p WHERE ta.userId=p.userId) as sum_payed
FROM ta 
GROUP BY ta.userId
)a
WHERE a.sum_costs <> a.sum_payed 
--ORDER BY a.userId;

Update: actually no need for ORDER BY UserId since it will be ordered implicitly by GROUP BY