int sel = int.Parse(0+dataGridView2.CurrentRow.Cells["invoice_ID"].Value.ToString());
string sql = "DELETE FROM invoices WHERE invoice_id="+ sel +"";
DBConnection myCon = new DBConnection();
myCon.EditValues(sql);
//mycon.EditeValues(sql) has all the sqldata reader,executenonQuery cmd
the error's arrow points out to the first line which is "int sel............".