Stored procedure to Validate duplicate insert for same Username

/****** Object:  StoredProcedure [dbo].[proc_IsExistUser]    Script Date: 09/18/2014 08:23:03 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

--exec [proc_IsExistUser] 'aa'   
CREATE Procedure [dbo].[proc_IsExistUser]          
 (       
  @UserName varchar(50)     
 )     
AS       
           
BEGIN      
       
 Begin Try     
  
   select * from View_Users where UserName =@UserName  
  
 End Try       
       
 BEGIN CATCH       
       
     return  '0';       
       
 END CATCH       
       
END
GO