CODEWITHSUNDEEP
sql-serversql-server-2008ssms
loviji
loviji

Reputation: 13080

Unique constraint on multiple columns

CREATE TABLE [dbo].[user](
        [userID] [int] IDENTITY(1,1) NOT NULL,
        [fcode] [int] NULL,
        [scode] [int] NULL,
        [dcode] [int] NULL,
        [name] [nvarchar](50) NULL,
        [address] [nvarchar](50) NULL,
     CONSTRAINT [PK_user_1] PRIMARY KEY CLUSTERED 
    (
        [userID] ASC
    )
    ) ON [PRIMARY]

    GO

How do I add a unique constraint for columns fcode, scode, dcode with t-sql and/or management studio? fcode, scode, dcode must be unique together.

Upvotes: 297

Views: 294791

Answers (4)

Tony L.
Tony L.

Reputation: 19396

This can also be done in the GUI. Here's an example adding a multi-column unique constraint to an existing table.

  1. Under the table, right click Indexes->Click/hover New Index->Click Non-Clustered Index...

enter image description here

  1. A default Index name will be given but you may want to change it. Check the Unique checkbox and click Add... button

enter image description here

  1. Check the columns you want included

enter image description here

Click OK in each window and you're done.

Upvotes: 71

Muhanned Kamil
Muhanned Kamil

Reputation: 9

USE [TSQL2012]
GO

/****** Object:  Table [dbo].[Table_1]    Script Date: 11/22/2015 12:45:47 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Table_1](
    [seq] [bigint] IDENTITY(1,1) NOT NULL,
    [ID] [int] NOT NULL,
    [name] [nvarchar](50) NULL,
    [cat] [nvarchar](50) NULL,
 CONSTRAINT [PK_Table_1] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
 CONSTRAINT [IX_Table_1] UNIQUE NONCLUSTERED 
(
    [name] ASC,
    [cat] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

Upvotes: 0

devmake
devmake

Reputation: 5262

By using the constraint definition on table creation, you can specify one or multiple constraints that span multiple columns. The syntax, simplified from technet's documentation, is in the form of:

CONSTRAINT constraint_name UNIQUE [ CLUSTERED | NONCLUSTERED ] 
(
    column [ ASC | DESC ] [ ,...n ]
)

Therefore, the resuting table definition would be:

CREATE TABLE [dbo].[user](
    [userID] [int] IDENTITY(1,1) NOT NULL,
    [fcode] [int] NULL,
    [scode] [int] NULL,
    [dcode] [int] NULL,
    [name] [nvarchar](50) NULL,
    [address] [nvarchar](50) NULL,
    CONSTRAINT [PK_user_1] PRIMARY KEY CLUSTERED 
    (
        [userID] ASC
    ),
    CONSTRAINT [UQ_codes] UNIQUE NONCLUSTERED
    (
        [fcode], [scode], [dcode]
    )
) ON [PRIMARY]

Upvotes: 324

marc_s
marc_s

Reputation: 754268

If the table is already created in the database, then you can add a unique constraint later on by using this SQL query:

ALTER TABLE dbo.User
  ADD CONSTRAINT ucCodes UNIQUE (fcode, scode, dcode)

Upvotes: 489

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