Question

I have a database with 3 tables. These tables represent membership information. I only want to retrieve results for groups that a specific user does NOT belong to. I’m not sure how to do this. Currently, I’m looking at the following:

SELECT
  g.*,
  a.*
FROM    
  GroupInfo g 
    INNER JOIN [Address] a ON a.[ID]=g.[AddressID]
    OUTER JOIN [GroupMembership] m ON m.[GroupID]=g.[ID]
WHERE
  m.[MemberID]<>@memberID

I’m concerned about accuracy and performance. Am I going the correct way?

Answer 1

Another approach is

 Select * From GroupInfo g Join Address a
     On a.Id = g.AddressId
 Where Not Exists
    (Select * From GroupMembership 
     Where GroupID = g.GroupID
        And MemberID = @memberID)