Prevent Duplicate Records on an MS SQL Database Column?

[Manuel]

How to prevent duplicate values in an SQL Management Studio Express column. I have a table where the Primary Key is the CountryID, then I have a CountryName column which I would like to prevent duplicate entries from occurring. Please indicate how to set this column property so it would not allow duplicates.Thanks!Manuel

[Ayesha]

Java tutorials-http://java-tip.org/

[Jay D]

Create an Index on the Country Name column specifying in the properties of the Index that it is Unique Is Unique = TrueThis should prevent duplicate Country names.Script FollowsUSE [MyDemo_DB]GO/****** Object: Table [dbo].[Country_TBL] Script Date: 08/13/2008 00:30:40 ******/SET ANSI_NULLS ONGOSET QUOTED_IDENTIFIER ONGOCREATE TABLE [dbo].[Country_TBL]([CountryID] [int] NOT NULL,[Country Name] [nchar](10) NOT NULL, CONSTRAINT [PK_Country_TBL] PRIMARY KEY CLUSTERED ([CountryID] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]USE [MyDemo_DB]GO/****** Object: Index [IX_Country_TBL] Script Date: 08/13/2008 00:33:25 ******/CREATE UNIQUE NONCLUSTERED INDEX [IX_Country_TBL] ON [dbo].[Country_TBL] ([Country Name] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

[sana p]

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