We are just trying to decide whether a record that lacks a foreign key should have the key listed as 0 or NULL. I think that 0 is easier to work with. For example, if we want to exclude records with a certain two foreign keys or no foreign key, we would say:

SELECT * FROM Table1 WHERE NOT INLIST(Foreign_Key, 13, 32, 0)

as opposed to

SELECT * FROM Table1 WHERE NOT INLIST(Foreign_Key, 13, 32) AND Foreign_Key IS NOT NULL


Jerry