Question

I have a Users table and a Payments table. I need a query which lists the users who DO NOT have a record in the payments table where the field PaymentCompleted=1.

These are the columns in the tables (simplified):

     Users: UserID, UserName
  Payments: PaymentID, UserID, PaymentCompleted

The query should select the field UserName.

Answer 1

select distinct UserName
from Users left outer join Payments on Users.UserID = Payments.UserID
where PaymentCompleted is NULL or PaymentCompleted != 1