Hi,

I have a database of users and I want to perform a check before I add a new user to the db, to ensure that the username does not exist already.

Currently I'm using a stored procedure to return the number of rows that match the new username: if the number > 0 then I issue the error message "Achtung. User exists already etc".

It works but is this the best way?

If you're using something like
SELECT Count(Username) FROM Users WHERE Username = 'NewUsersname'
then you should be alright. There's no major issue with doing it that way.

(Hint: Since you're returning a single value from a single row, you can use ExecuteScalar to improve efficiency)

Another way to do it would be to make sure all that field in the database is indexed, and then catch the errror that you get when you try to insert a duplicate username.

Thanks Minaki!

I didn't know whether there was some kind of 'best practice' to follow for this kind of thing.

I think I'll carry on retrieving the record count but use ExecuteScalar like you suggested.

The way i do it is via a datareader.

My SQL statement tries to select the user with the username they want to register, if the datareader reads, the username exists -> error message.

If not, i call another function to add the user.

Yeah, that's similar to the way I was doing it. Nice to know I was on the right track!

Thanks sc.