>Can I add a constraint to a table to ensure that a column is unique? The column is not the PK column.
>Considder the following table:
>

>CREATE TABLE [dbo].[User](
>	[UserId] [uniqueidentifier] NOT NULL,
>	[Login] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
>	[Password] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
>	[FirstName] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
>	[LastName] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
>CONSTRAINT [PK_User] PRIMARY KEY CLUSTERED
>(
>	[UserId] ASC
>)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
>) ON [PRIMARY]
>

>
>I would like to make the Login column unique.

CREATE TABLE [dbo].[User](
	[UserId] [uniqueidentifier] NOT NULL,
	[Login] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
	[Password] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
	[FirstName] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
	[LastName] [nvarchar](30) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
CONSTRAINT [PK_User] PRIMARY KEY CLUSTERED
(
	[UserId] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
CREATE UNIQUE NONCLUSTERED INDEX IX_User_1 ON dbo.User_1
	(
	Login
	) WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

This script is generated by SQL MS