Question

I’m having a table (an existing table with data in it) and that table has a column UserName. I want this UserName to be unique. So I add a constraint like this:

ALTER TABLE Users  ADD CONSTRAINT [IX_UniqueUserUserName] UNIQUE NONCLUSTERED ([UserName]) 

Now I keep getting the Error that duplicate users exist in this table. But I have checked the database using the following query:

SELECT COUNT(UserId) as NumberOfUsers, UserName  FROM Users  GROUP BY UserName, UserId  ORDER BY UserName 

This results in a list of users all having 1 as a NumberOfUsers. So no duplicates there. But when I’m checking the username he fails I see the following result:

beluga béluga 

So apperently he fails to compare an ‘e’ and ‘é’ or ‘è’ … It’s like he ignores these, is there any way that sql doesn’t ignore these accents when adding the unique key contraint.

SOLUTION:

THX to you guys I’ve found the solution. This fixed the problem:

ALTER TABLE Users  ALTER COLUMN UserName nvarchar(250) COLLATE SQL_Latin1_General_CP1_CI_AS 

Answer 1

The collation you are using most likely ignores case and accents when comparing. You’ll need to change the collation.

• Latin1_General_CI_AI Ignores case and accents
• Latin1_General_CI_AS will not ignore accents

List of SQL server collation names here.