private void Select_Bill_ID_for_return_bill_SelectedIndexChanged(object sender, EventArgs e) { DataTable table = new DataTable(); conn = new OracleConnection(ordb); conn.Open(); OracleCommand cmd = new OracleCommand(); cmd.Connection = conn; cmd.CommandText = "select * from Bill where Bill_ID =:idd"; cmd.CommandType = CommandType.Text; cmd.Parameters.Add("idd", int.Parse(Select_Bill_ID_for_return_bill.SelectedItem.ToString())); OracleDataReader dr = cmd.ExecuteReader(); table.Columns.Add("Bill_ID", typeof(float)); table.Columns.Add("Total_price", typeof(float)); table.Columns.Add("Bill_date", typeof(string)); table.Columns.Add("Customer_id", typeof(int)); table.Columns.Add("Delivery_boy_ID", typeof(int)); table.Columns.Add("Delivery_Charges", typeof(float)); table.Load(dr); dataGridView_for_return_Products.DataSource = table; ///////////////////////////////////////////////////////////////// textBox_product_name.Show(); label_return.Show(); Ok_button_Product_name.Show(); DataTable tablee = new DataTable(); OracleCommand cm = new OracleCommand(); cm.Connection = conn; cm.CommandText = "select PRODUCTS_NAME from LIST_OF_BILL_PRODUCTS where Bill_ID =:id"; cm.CommandType = CommandType.Text; cm.Parameters.Add("id", int.Parse(Select_Bill_ID_for_return_bill.SelectedItem.ToString())); OracleDataReader dre = cm.ExecuteReader(); tablee.Columns.Add("PRODUCTS_NAME", typeof(string)); tablee.Load(dre); dataGridView_Product_name.DataSource = tablee; }