NULL questions

lividsp

Am I assuming correctly when I asume that there is a difference between NULL and " ".

I ask this becuase I have an email field in my database that is an optional piece of information for my client. And if the data fileld is left blank in the form, I want the value in the data base to be represented as null.

I have been unsuccessful in my attemps.

I can get the value to " " or empty as I call it, but I am not sure it is the same as NULL.

any ideas?

MrAlaska

I do not work with NULL so I cannot help you with the syntax for working with NULL values, but yes there is a difference.

I can't find the article, but I read one that presented the case that you should avoid allowing NULL unless you really need it. The article mentioned, among other things, that the very least you will do is save a few bytes in every row by making each field NOT NULL default="". There were some other performance considerations as well.

hand

http://www.mysql.com/doc/en/Problems_with_NULL.html

sid

Originally posted by lividsp
Am I assuming correctly when I asume that there is a difference between NULL and " ".

I ask this becuase I have an email field in my database that is an optional piece of information for my client. And if the data fileld is left blank in the form, I want the value in the data base to be represented as null.

I have been unsuccessful in my attemps.

I can get the value to " " or empty as I call it, but I am not sure it is the same as NULL.

any ideas?

to compare null values you have to use IS NULL and IS NOT NULL in the hwere clause

f.ex. "SELECT * FROM users WHERE suspended IS NULL"
or "DELETE FROM users WHERE suspended IS NOT NULL"

this should work

rock on sid