In this SQL Server tip, Arthur Fuller explains the effects of NULLs, and the different results obtained by inner and outer JOINs.

This example illustrates a left outer join of the PROCLIB.PAYROLL and PROCLIB.PAYROLL2 tables. proc sql outobs=10; title 'Most Current Jobcode and Salary Information'; select p.IdNumber, p.Jobcode, ...

I need to form the equivalent of a Union Join in Oracle 8i, even though a Union Join doesn't appear to be supported in 8i. I might be able to manipulate a Full Outer Join to get the results I need ...