Adding constraint to varchar type column

Question

Hi,

I have a table as below

CREATE TABLE [dbo].[tblLocationMaster](
  [LocationID] [int] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,
  [LocationName] [varchar](50) NOT NULL,
  [Description] [varchar](500) NULL,)

I want to add a constraint on LocationName so that duplicate values do not get saved in table... How to do this?