empty string, NULL, NOT NULL

Hello,

could you tell me for a field what these things would mean viz. if I say a colume as allows NULL and then if its varchar2, could I use in where clause empty string? where col = ''
I tried it and it was not matching it. so could one explain me if '' and NULL are same or is '' a valid empty string.

Then when I say the col as NOT NULL can I insert '' into it for varchar2.

I guess If am clear with my doubt would you email me at:

mehta_at_mama.indstate.edu

Thanks.

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Thu Jan 06 2000 - 09:58:43 CST