public List <StockOut> soldItems(DateTime startDate, DateTime endDate)
        {
            List <StockOut> allSales = new List <StockOut>();

            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand();
                cmd.CommandText = " SELECT * FROM tbl_SalesSheet WHERE StockOutTime BETWEEN @StartTime AND @EndTime;";
                cmd.Parameters.AddWithValue("@StartTime", startDate);
                cmd.Parameters.AddWithValue("@EndTime", endDate);
                cmd.Connection = connection;
                connection.Open();
                SqlDataReader reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    StockOut aSale = new StockOut();
                    aSale.GetSales(reader["ItemName"].ToString(), Convert.ToInt32(reader["Quantity"]));
                    allSales.Add(aSale);
                }
                reader.Read();
                connection.Close();
                return(allSales);
            }
        }