Question

I am trying to write a query that will return what hosts are missing a piece of software:

Host                    Software
A                       Title1
A                       Title2
A                       Title3 
B                       Title1
B                       Title3
C                       Title4
C                       Title3

How to query for which hosts are missing Title2 (should be B and C)? I’ve tried GROUP BY, HAVING and subquery using COUNT but I don’t seem to have the right idea.

Answer 1

SELECT Host FROM HostSoftware
WHERE NOT EXISTS (
    SELECT * FROM HostSoftware AS InnerSoftware
    WHERE InnerSoftware.Host = HostSoftware.Host AND InnerSoftware.Software ='Title2'
)