CODEWITHSUNDEEP
sql-serveruniquevarchar
Tomas
Tomas

Reputation: 18097

Make a varchar(50) column unique

I have a column (which represents an e-mail) in a SQL Server database with varchar(50) as data type and I would like to make it unique (do not allow the same two e-mail addresses). I cannot find a way to make such column unique in SQL Server Management Studio.

How to do that?

Upvotes: 23

Views: 37855

Answers (3)

gbn
gbn

Reputation: 432200

In T-SQL it would be

ALTER  TABLE  MyTable WITH CHECK 
   ADD CONSTRAINT UQ_MyTable_Email UNIQUE (EmailAddress)

Or as an explicit index

CREATE  UNIQUE INDEX IXU_Email ON MyTable (EmailAddress)

Edit: I can't see how to create a constraint in the SSMS GUI: other answers show how to manage indexes. I do only use SQL though, never the GUI for this kind of work

Upvotes: 39

Barry Kaye
Barry Kaye

Reputation: 7761

In the Object Explorer under the table right-click the Indexes folder and choose New Index....

In the window that appears enter Index name:, tick the Unique checkbox and add your email field from the Add... button then click OK.

Upvotes: 7

Nonym
Nonym

Reputation: 6299

Try this:

ALTER TABLE [dbo].[TableName] ADD CONSTRAINT UNQ__TableName__ColumnName UNIQUE ([ColumnName])

From this:

http://msdn.microsoft.com/en-us/library/ms191166.aspx

Upvotes: 3

Related Questions