Opposite of inner join

Question

What will be the opposite of inner join? For a table table Person (int PersonId, varchar PersoName, int AddrId), I want to know the rows in Person with bad Ad

Answer 1

I think the best solution would be using EXISTS. Like this:

SELECT * FROM Person P
WHERE P.AddrId IS NOT NULL 
  AND NOT EXISTS ( SELECT 1 FROM Address A WHERE A.AddrId = P.AddrId )

The query above will return every person that the AddrId is set but does not have a corresponding record in the Address table.

Obs.: Use the constant 1 in the EXISTS query to avoid table access.