SQL Server - NOT IN

Question

I need to build a query that will show me records that are in Table 1, but that are not in Table 2, based on the make-model-serial number combination.

I know for fac

Answer 1

One issue could be that if either make, model, or [serial number] were null, values would never get returned. Because string concatenations with null values always result in null, and not in () with null will always return nothing. The remedy for this is to use an operator such as IsNull(make, '') + IsNull(Model, ''), etc.