ALTER PROCEDURE [dbo].[SP_Student]
@StudentId varchar(50)
,@Name varchar(MAX)
,@Roll varchar(6)

AS
BEGIN TRAN
IF(@StudentId = 0) --Insert
BEGIN
SET @StudentId = (SELECT MAX(StudentId) FROM Student) + 1

INSERT INTO Student  (StudentId, [Name], Roll)
           VALUES(@StudentId, @Name, @Roll)

SELECT * FROM Student WHERE StudentId=@StudentId

END
ELSE IF(@StudentId > 0) --Update
BEGIN
IF (@StudentId = 0)
BEGIN
ROLLBACK
RAISERROR (N'Invalid Student !!!~',16,1);
RETURN
END

UPDATE Student SET [Name]=@Name
   ,Roll=@Roll
WHERE StudentId=@StudentId

SELECT * FROM Student WHERE StudentId=@StudentId
END
COMMIT TRAN