Do I need a Identity Specification(self increment) column if I already have a unique column that I can use as key?

Hi, I'm using ms sql 2012.
I'm creating a user table and I wonder when is the case when I should have a self infringement column as a Key for the table?  I'm already going to store Windows users ID in this table so shouldn't I just use this as the key?  Is there any reason that I shouldn't or there is some advantage using the Int Identity Specification type column?
thank you.
lapuccaAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Jim HornMicrosoft SQL Server Data DudeCommented:
Two reasons to use an identity field

1.

An int is only 4 bytes, whereas a character column is going to be roughly one byte per character, depending on unicode or varchar.

2.

If you're ever in a situation where the Windows user id changes due to marriage, divorce, sex change, inserting a new domain's worth of people, whatever, then you're covered. If neither of these are that big a deal, then go ahead and use the Windows user id.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Kent OlsenDBACommented:
Any unique key can be used as a foreign key.

Note that an integer is typically the fastest data type for join operations.  If your key is a string you should consider changing the key to an IDENTITY column for performance purposes.

Also, the IDENTITY value will never change.  Data can change.  And if you're using data as your primary key you run the risk of conversion/migration issues if you ever need to change the data.


Kent
lapuccaAuthor Commented:
Makes a lot of sense.  Thank you.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Microsoft SQL Server

From novice to tech pro — start learning today.