Question

I have 2 tables, contracts and salesmen.
Recently I’ve discovered some errors in the data, some contracts have salesid’s not found in ‘salesmen’, I suspect an accidental deletion or an input error of some kind.

Which join should I use to find all contracts that dont ‘belong’ to a salesman, in other words, the contract.salesid not found in the salesmen.id column.

It should be a right outer join but the results arent coming up right.

Answer 1

SELECT c.contract_id FROM contract c
LEFT OUTER JOIN salesmen s ON s.salesman_id = c.salesman_id
WHERE c.salesman_id IS NULL

would be my guess.