to null or not to null

I know the answer is in a book somewhere but I have been reading so much my eyes are . What is the differance between null and not null, why or how should I use it.

Thanks D. E. L.

Hi,



The NULL value means "no data".

It is different from values such as 0 for numeric types or the empty string for string types.

Of course, NOT NULL is just opposite to NULL definition.It should hold some data.


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SR -
shiju.dreamcenter.net

"The fear of the LORD is the beginning of knowledge..."

[This message has been edited by Shiju Rajan (edited May 17, 2000).]

Nullable fields should be used to keep track of data where it may or may not be available when the data is entered. If you choose not to have null fields, and the information for the field is not available when the data is loaded, you will need to have some sort of default that takes the place of the null.
Not null is usually the preferred way of setting up fields, because it saves the overhead of the null indicator in both storage and search capabilities.