Question

I have a table with user payment details, and another table with a list of users. I want to get the balance of all users from the payment details, but only for users that are not banned (which is a column in the users table).

I am somewhat new to nested queries so I am not sure how to do this?

Here is what I have tried so far…

mysql_query("
    SELECT SUM(balance) 
    FROM payment_details 
    WHERE (SELECT ban 
           FROM users 
           WHERE username=username
          ) != '1'
")

Note: Username is a column in both tables.

The above query does not work.

To Recap: There are two tables: payment_details and users. I want to add together the balance column for all the users that are not banned.

Answer 1

Don’t use a subquery here. Instead, use a JOIN.

SELECT SUM(payment_details.balance) FROM payment_details
JOIN users ON payment_details.username = users.username
WHERE ban != '1'