[snip]
Were you using two tables with a one-to-many relationship of the
joining field? As in
table 1 table 2
prodID (p/k) prodID inventoryID (p/k)
100001 100001 1
100002 ----+--> 100002 2
100003 +--> 100002 3
100004 +--> 100002 4
[/snip]
Yes, it was a one to many relationship on the two tables.