> I was faced with a similar issue. One suggestion I got from the Internet > was to create a shadow column that contains the values used in the Index, > with a dummy entry (in my case, the string <NULL>) for those records in > which the primary column is NULL. It works well for my app. Michael, thank you. This is not working in my case. Uniquenes sis not sufficient: I need referential integrity with uniqueness. If I add <NULL> department, this must be added into department table also and pollutes this table. Andrus. ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly