unique username in user table - Xtreme Visual Basic Talk

08-25-2008, 01:50 AM

peanutong

Newcomer

Join Date: Aug 2008

Posts: 2

unique username in user table

how do i create restrictions whereby there cannot be two similar username in the table, while registering?

i am using SQL server.

thank you.

08-25-2008, 07:15 AM

gpraceman

Contributor

* Expert *

Join Date: Sep 2002

Location: Highlands Ranch, CO

Posts: 556

Just run a query to verify that the new user name doesn't already exist in the table first, then do the insert.

__________________
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.

08-25-2008, 07:35 AM

wayneph

Web Junkie

Retired Moderator
* Expert *

Join Date: Apr 2004

Location: D/FW, Texas, USA

Posts: 8,393

It's better to add a Constraint on the table so that SQL doesn't allow the second occurance in. A Primary or Unique Constraint on the Username column should do the trick in this case.

What happens when there are multiple developers on a project and not everyone codes the same checks in? I'm not saying that the application shouldn't check to see if it's there, but the responsibility for clean data should be held in the database design.

__________________
-- wayne, MSSM Retired
> SELECT * FROM users WHERE clue > 0
0 rows returned

08-25-2008, 07:42 AM

gpraceman

Contributor

* Expert *

Join Date: Sep 2002

Location: Highlands Ranch, CO

Posts: 556

Quote:

Originally Posted by wayneph

What happens when there are multiple developers on a project and not everyone codes the same checks in? I'm not saying that the application shouldn't check to see if it's there, but the responsibility for clean data should be held in the database design.

So true.

__________________
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.