Rune Bivrin (9/24/2010)
It's back to avoiding unneccesary NULL:s. If you need them by all means use them. Just make sure that you have good a motivation why a column should be NULL-able.
Exactly! I object to the advise to "avoid NULLs" (as given in Books Online). But I'll be the first that attempts to design without NULLs are not even half as bad as designs where every column allows NULLs. (And unfortunately, the latter is far more common than the former).
I hardly do any front-end work at all, I am mostly database developer and somewhat DBA, but I've done and seen enough to know that NULLs are, indeed, a pain in 3GL and OO languages. (Though most application problems do not come from the handling of NULLs being hard, but from the app developers having no clue)