cannot find table 0 in c# asp.net

Question

                if (ds.Tables[0].Rows.Count > 0)
                {
                    txtid.Text = ds.Tables[0].Rows[0]["id"].ToString();
                    txttamil.Text = ds.Tables[0].Rows[0]["Tamil"].ToString();
                    txtenglish.Text = ds.Tables[0].Rows[0]["English"].ToString();
                    txtmaths.Text = ds.Tables[0].Rows[0]["Maths"].ToString();
                    txtscience.Text = ds.Tables[0].Rows[0]["Science"].ToString();
                    txtsocialscience.Text = ds.Tables[0].Rows[0]["SocialScience"].ToString();
                }

            }

In the above showed error 'cannot find table 0'.

When i enter invalid id, it need to show "ID does not exist".

May i know, what my mistake in my code?

stored procedure:

ALTER PROCEDURE sp_studentresult
(
    @id int,
    @output varchar(50) output,
    @id_student varchar(50)
)
AS

IF EXISTS (SELECT * FROM student WHERE id=@id_student)
BEGIN
SELECT * from studentresult where id_student=@id
END
ELSE
BEGIN
SET @output='Doesn not EXIST'
End

any help would be highly appreciated. Thanks,

Answer 1

There is no point on complicating your sp with logic.

Why don't you just check if the query has returned any data?

if (ds.Tables[0].Rows.Count > 0)
{
    txtid.Text = ds.Tables[0].Rows[0]["id"].ToString();
    txttamil.Text = ds.Tables[0].Rows[0]["Tamil"].ToString();
    txtenglish.Text = ds.Tables[0].Rows[0]["English"].ToString();
    txtmaths.Text = ds.Tables[0].Rows[0]["Maths"].ToString();
    txtscience.Text = ds.Tables[0].Rows[0]["Science"].ToString();
    txtsocialscience.Text = ds.Tables[0].Rows[0]["SocialScience"].ToString();
}
else
{
    // Whatever you want to do if no row is found
}

And a simpler sp, which will return a empty table if nothing is found

ALTER PROCEDURE sp_studentresult
(
    @id int
)
AS

-- I have removed the extra id column as not sure why you use it
SELECT * from studentresult where id_student=@id

Answer 2

Your SP doesn't return any tabular data in case of a non existing id. Try change it to something like

IF NOT EXISTS (SELECT * FROM student WHERE id=@id_student)
BEGIN
    SET @output='Does not EXIST'
END
SELECT * from studentresult where id_student=@id