Question

My code is as shown below :

using (SqlConnection _conn = new SqlConnection(ConfigurationManager.ConnectionStrings["DarmanConnectionString"].ToString()))
{
    using (SqlCommand _cmd = new SqlCommand("dbo.sp_Noskheh_SumOfTotalPay", _conn))
    {
        _cmd.CommandType = CommandType.StoredProcedure;
        _cmd.Parameters.Add(new SqlParameter("@Co_ID", int.Parse(Session["Co_ID"].ToString())));

        _cmd.Parameters.Add(new SqlParameter("@RETURN_VALUE", SqlDbType.NVarChar));
        _cmd.Parameters["@RETURN_VALUE"].Direction = ParameterDirection.ReturnValue;

        _conn.Open();
        _cmd.ExecuteNonQuery();

        Int64 result = Int64.Parse(_cmd.Parameters["@RETURN_VALUE"].Value.ToString());
        lblSumTotalPayShow.Text = result.ToString();

            _conn.Close();
        }
    }

my SP is like this :

create Procedure [dbo].[sp_Noskheh_SumOfTotalPay]
    @Co_ID int
As    
    -----------------
    Declare @Sum nvarchar(50)
    -----------------    
BEGIN
    Select @Sum = convert(nvarchar(50), SUM(TotalPay))
    From Noskheh
    Where (Co_ID = @Co_ID)

    Return @Sum
END

and the error is in line (_cmd.ExecuteNonQuery();):

Error:

Sys.WebForms.PageRequestManagerServerErrorException: The conversion of
the nvarchar value ‘3955811801’ overflowed an int column. The
‘sp_Noskheh_SumOfTotalPay’ procedure attempted to return a status of
NULL, which is not allowed. A status of 0 will be returned instead.

Would you please help me to figure out this problem?

Answer 1

You are trying to convert a nvarchar value to a int

The Return statement must be an integer.

Try changing your approach and in your Stored Proc do

Select @Sum instead of return @sum

Then instead of using ExecuteNonQuery use ExecuteScalar

String result = (String)cmd.ExecuteScalar();
lblSumTotalPayShow.Text = result.ToString();