Difference Between Primary Key and Foreign Key in SQL

Difference Between Primary Key and Foreign Key

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Set Primary Key,Unique Key,Foreign Key Sql Server Database Table in Visual Studio

Set Primary Key,Unique Key,Foreign Key


Set to Primary Key ,Foreign Key , Unique Key Sql Server DataBase Table Fields  Using Visual Studio


DEMO

Primary Key


     CREATE TABLE [dbo].[country] (

    [id]      INT          IDENTITY (1, 1) NOT NULL,

    [name]    VARCHAR (50) NOT NULL,

    [country] VARCHAR (50) NOT NULL,

    [amount]  VARCHAR (50) NOT NULL,

    

   CONSTRAINT [PK_country] PRIMARY KEY CLUSTERED ([id] ASC),

   

  );

Unique Key

CREATE TABLE [dbo].[country] (

    [id]      INT          IDENTITY (1, 1) NOT NULL,

    [name]    VARCHAR (50) NOT NULL,

    [country] VARCHAR (50) NOT NULL,

    [amount]  VARCHAR (50) NOT NULL,

    CONSTRAINT [PK_country] PRIMARY KEY CLUSTERED ([id] ASC),

    UNIQUE NONCLUSTERED ([name] ASC)

);

Foreign Key

CREATE TABLE [dbo].[register] (

    [username] VARCHAR (50) NOT NULL,

    [password] VARCHAR (50) NOT NULL,

    [country]  VARCHAR (50) NOT NULL,

    [name]     VARCHAR (50) NOT NULL,

    CONSTRAINT [FK_reg_country] FOREIGN KEY ([name]) REFERENCES [dbo].[country] ([name])

);

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