Question

I’ve got a table called transaction

Transaction:
  User_Id: int
  Transaction_Type: int
  Amount: int

How would I query all users that do not have transaction type 1.

SELECT * FROM Transaction WHERE Transaction_Type <> 1 Group By User_Id

seems to return all users & their transaction types that are not = to 1. I need all users that are missing / have no record of type 1.

Answer 1

This can be done with an IN() subquery

SELECT DISTINCT User_Id FROM Transaction
WHERE User_Id NOT IN (SELECT DISTINCT User_Id FROM Transaction WHERE Transaction_Type = 1)

Or with a NOT EXISTS

SELECT
  DISTINCT User_Id 
FROM Transaction t
WHERE
  NOT EXISTS (SELECT User_Id FROM Transaction tn WHERE Transaction_Type = 1) 
  AND t.User_Id = tn.User_Id