Re: Does NULL == ""?

[Brent Baisley]

This is sometime a tough concept to get through. For example, there is 
more than two answers to a yes and no question. There is yes, no, "I 
don't know" (the empty set) and the "No answer at all" (null).
It's almost useless to specify a property as NOT NULL and also set a 
default value. The only way it would ever be NULL is if you 
specifically set it to NULL. If you see an empty field in a database, 
you have to wonder if someone forgot to enter a value or if there was 
no value to enter. The difference between NULL (no value entered) and 
"" (no value to enter).


On Monday, September 15, 2003, at 11:00 AM, Randy Chrismon wrote:

> The MySQL documentation confuses me a bit. If I create a table with
> property NOT NULL and default "", does that mean that a record with a
> column so defined will have a zero-length string in that column if I
> don't provide a value? I guess what I'm asking is whether there's a
> difference between a field with NULL in it and a field with a
> zero-length ("") string in it.
>
-- 
Brent Baisley
Systems Architect
Landover Associates, Inc.
Search & Advisory Services for Advanced Technology Environments
p: 212.759.6400/800.759.0577