Reflect sum of column to a label on a WinForm

I want to reflect the sum of a column to a label on a WinForm. I don't know what's wrong with this code:

private void btnT_Click(object sender, EventArgs e)
{
SqlConnection cn = new SqlConnection("data source = TURKY-PC ; initial
catalog = coffeeshopDB ; integrated security = true ; ");
SqlCommand cmd;
SqlDataReader dr;
cmd = new SqlCommand("select SUM (cost) from billTB", cn);
cn.Open();
dr = cmd.ExecuteReader();
while (dr.Read())
{
btnT.Text = dr["cost"].ToString();
}
dr.Close();
cn.Close();
}


The error exception that appears is: System.IndexOutOfRangeException: 'cost'

System.IndexOutOfRangeException: 'cost'

1 Answer
1

If you're going to refer to the column by name, you have to name the result of the SUM. You also don't need a loop in this case, because you know there's only one row.

SUM

private void btnT_Click(object sender, EventArgs e)
{
SqlConnection cn = new SqlConnection("data source = TURKY-PC ; initial
catalog = coffeeshopDB ; integrated security = true ; ");
SqlCommand cmd;
SqlDataReader dr;
cmd = new SqlCommand("select SUM (cost) as TotalCost from billTB", cn);
cn.Open();
dr = cmd.ExecuteReader();
dr.Read();
btnT.Text = dr["TotalCost"].ToString();
dr.Close();
cn.Close();
}


big thanks Ken that works thanks bro
– Ezel Berkdar
2 days ago

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