How to avoid duplicate record in SQL Server?

ER sandeep chourasia
sandeepchrs@yahoo.com (on facebook)
http://www.aspnetcodes.com/

IF Not Exists(SELECT 1 FROM UserTable WHERE UserName = @userName)

Begin

      INSERT INTO UserTable (UserName) VALUES (@userName)

End

Himanshu Manjarawala
Sr. Software Engineer@AutomationAnywhere
http://fieredotnet.wordpress.com/

create proc [dbo].[sp_InsPersonInfo]

@pEmail varchar(50)

as

declare @Count as int

set @Count=(select count(id) from Persons where PersonEmail=@pEmail)

select @Count as DuplicateEmail

if @Count=0

begin

insert into Persons values(@pEmail)

end

protected void btnSubmit_Click(object sender, EventArgs e)

    {

      BAL = new PersonBusinesslayer();

ds = new DataSet();        ds=BAL.Insert(txtEmail.Text);

      int Count;

Count = Convert.ToInt32(ds.Tables[0].Rows[0]["DuplicateEmail"].ToString());

      if (Count > 0)

      {

string strjscript = "<script language='javascript'>

alert('Email id already exists ');</script>";

Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "myscript",   strjscript);

      }      

    }

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Thanks,
Sanjay

sriram

DECLARE @Count int

	SELECT @Count = Count(AutoID) FROM UserTable WHERE UserName = @userName

	IF @Count = 0

		BEGIN

			INSERT INTO UserTable (UserName) VALUES (@userName)

		END

Regards,
Raja, USA