Topic: Very General Question: Purpose of NULL

[exit44]

I have a very general question about database design.  What is the purpose of allowing a field to be set to a NULL value in a database field.  I have been building for a while and have really never used this setting.  I always just test the output before displaying to the browser and if the field is empty I treat it accordingly.  What are the advantages of NULL over this or does it have other purposes?

Thanks!

[aeroswat]

Maybe this will be helpful to you

http://www.informit.com/guides/content.aspx?g=sqlserver&seqNum=215

I have also recently found a great use for NULL values. I required the ability to find all the rows in one table that could not relate to a row in another table based on the joining key. The only way to display these were to display only rows in which the joining key was NULL.

[exit44]

Very helpful article.  Thank you for posting it for me.