void FeedStockData(MySql.Data.MySqlClient.MySqlCommand msqlCommand, BillingData billData) { int dbQuantity = 0; //open the connection if (msqlConnection.State != System.Data.ConnectionState.Open) msqlConnection.Open(); msqlCommand.CommandText = "SELECT quantity_available FROM stock WHERE id='" + billData.productId + "';"; MySql.Data.MySqlClient.MySqlDataReader msqlReader = msqlCommand.ExecuteReader(); while (msqlReader.Read()) { dbQuantity = int.Parse(msqlReader.GetString("quantity_available")); } if (msqlConnection.State == System.Data.ConnectionState.Open) msqlConnection.Close(); //updating the value if (msqlConnection.State != System.Data.ConnectionState.Open) msqlConnection.Open(); String newQuantity = (dbQuantity - billData.quantity).ToString(); msqlCommand.CommandText = "UPDATE stock SET quantity_available='" + newQuantity + "' WHERE id='" + billData.productId + "'; "; msqlCommand.ExecuteNonQuery(); if (msqlConnection.State == System.Data.ConnectionState.Open) msqlConnection.Close(); }