Question

We have two tables:

— users —

id  name    borrower
--  ------  --------
1   Peter   1
2   John    1
3   Mark    1
4   David   0

— lendings —

id  from  to  amount
--  ----  --  ------
1   1     2   100

I need to output users that Peter hasn’t lent any money and that are borrowers=1 (excluding Peter from the results), like this:

id  name    borrower
--  ------  --------
3   Mark    1

Right now I am stuck with this query (doesn’t work):

SELECT * 
FROM `users` u 
LEFT OUTER JOIN `lendings` l
ON u.`id` = l.`from`
WHERE l.`from` is null
AND u.`id` != 1
AND u.`borrower` = 1

This is a simplified example of the actual code to keep the question useful/readable for future readers.

Related question: MySQL: select emails from one table only if not in another table?

Answer 1

Something like this?

SELECT 
    *
FROM
    users
WHERE
    id NOT IN (SELECT 
            id
        FROM
            lendings)
        AND borrower = 1;

You might want to use different column names as I believe from and to are reserved words in mysql.