invalid cast

ta mu

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;

            }

7 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes13y ago
Accepted 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();
0
ta mu13y ago
i got system.DBnull

now how i can manage it

thanks for reply
0
Vulpes13y ago
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();
0
ta mu13y ago
i try both these same error any other way

0
Vulpes13y ago
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.
0
ta mu13y ago
same error at

result = (int)temp; Specified cast is not valid.

result value is zero

0
Vulpes13y ago
Try:

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