invalid cast

Question

i have this code on button click when there is no record between selected dates therfore nothing is to sum as below i shown i got error "Specified cast is not valid." how i can do that if there is no record show a messag

private void button2_Click(object sender, EventArgs e)
        {
            label4.Text = "";
            try
            {
                my.Open();
                DataTable dt = new DataTable();
                SqlDataAdapter da = new SqlDataAdapter("Select * from add_investor Where date>='" + dateTimePicker1.Value + "'AND date<='" + dateTimePicker2.Value + "' ", my);
                da.Fill(dt);
                dataGridView1.DataSource = dt.DefaultView;
                my.Close();

                using (SqlCommand cmd = new SqlCommand("SELECT SUM(investor_amount) FROM add_investor WHERE date>='" + dateTimePicker1.Value + "'AND date<='" + dateTimePicker2.Value + "' ", my))
                {
                    my.Open();
                    int result = (int)cmd.ExecuteScalar();----------------------------------------error
                    label4.Text = result.ToString();
                    my.Close();
                }
            }

            catch
            {
                throw;

            }

Vulpes · Answer

OK let's try this: my.Open(); object temp = cmd.ExecuteScalar(); if (!DBNull.Value.Equals(temp)) { int result = (int)temp; label4.Text = result.ToString(); } else { MessageBox.Show(There are no records between those dates.); } my.Close();

ta mu · Answer

i got system.DBnull now how i can manage it thanks for reply

Vulpes · Answer

Let's see if we can find out what type of value is being returned: my.Open(); object temp = cmd.ExecuteScalar(); MessageBox.Show(temp.GetType().ToString()); // what do you see here? int result = 0; // say // if (temp != null) result = (int)temp(); // comment out for now label4.Text = result.ToString(); my.Close();

ta mu · Answer

i try both these same error any other way

Vulpes · Answer

Are you in fact expecting the result to be an int? If you're summing investor_amounts I'd have thought that double or decimal would be more likely.

ta mu · Answer

same error at result = (int)temp; Specified cast is not valid. result value is zero

Vulpes · Answer

Try: my.Open(); object temp = cmd.ExecuteScalar(); int result = 0; // say if (temp != null) result = (int)temp; label4.Text = result.ToString(); my.Close();