No, NULL is not the same as the empty string. NULL, for any class of field,
means that no data has ever been written there. Tests involving NULL other
than IS NULL and IS NOT NULL will return NULL. Thus "" < "a" returns 1
(true) whereas NULL < "a" returns NULL, which will always be regarded as a
"miss" in any select.
|---------+---------------------------->
| | "Randy Chrismon" |
| | <[EMAIL PROTECTED]|
| | ia.net> |
| | |
| | 15/09/2003 16:00 |
| | |
|---------+---------------------------->
>------------------------------------------------------------------------------------------------------------------------------|
|
|
| To: [EMAIL PROTECTED]
|
| cc:
|
| Subject: Does NULL == ""?
|
>------------------------------------------------------------------------------------------------------------------------------|
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.
Thanks.
Randy
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