Question

I want to pull back results from one table that match ALL specified values where the specified values are in another table. I can do it like this:

SELECT * FROM Contacts 
WHERE 
EXISTS (SELECT 1 FROM dbo.ContactClassifications WHERE ContactID = Contacts.ID AND ClassificationID =  '8C62E5DE-00FC-4994-8127-000B02E10DA5')
AND EXISTS (SELECT 1 FROM dbo.ContactClassifications WHERE ContactID = Contacts.ID AND ClassificationID =  'D2E90AA0-AC93-4406-AF93-0020009A34BA')
AND EXISTS etc...

However that falls over when I get up to about 40 EXISTS clauses. The error message is “The query processor ran out of internal resources and could not produce a query plan. This is a rare event and only expected for extremely complex queries or queries that reference a very large number of tables or partitions. Please simplify the query.”

Answer 1

The gist of this is to

• Select all contacts with any GUID from the IN statement
• Use a DISTINCT COUNT to get a count for each contactid on matching GUID’s
• Use the HAVING to retain only those contacts that equal the amount of matching GUID’s you’ve put into the IN statement

SQL Statement

SELECT *
FROM   dbo.Contacts c
       INNER JOIN (
          SELECT c.ID
          FROM   dbo.Contacts c
                 INNER JOIN dbo.ContactClassifications cc ON c.ID = cc.ContactID
          WHERE  cc.ClassificationID IN ('..', '..', 38 other GUIDS)
          GROUP BY
                 c.ID
          HAVING COUNT(DISTINCT cc.ClassificationID) = 40
       ) cc ON cc.ID = c.ID

Test script at data.stackexchange