void WriteHistoryToDatabaseEntityClickCommand()
        {
            using (var db = new HistoryContext())
            {
                foreach (ListViewData item in ListViewCollection)
                {
                    var hist = new History();

                    hist.Number       = int.Parse(item.ListView_No);
                    hist.a            = double.Parse(item.ListView_a);
                    hist.b            = double.Parse(item.ListView_b);
                    hist.c            = double.Parse(item.ListView_c);
                    hist.Discriminant = double.Parse(item.ListView_Discriminant);
                    hist.x1           = item.ListView_x1;
                    hist.x2           = item.ListView_x2;
                    hist.dbDateTime   = item.ListView_Datetime;

                    db.Histories.Add(hist);
                }
                db.SaveChanges();
            }
        }
        void WriteHistoryToDatabaseEntityClickCommand()
        {
            using (var db = new HistoryContext())
            {
                foreach (ListViewData item in ListViewCollection)
                {
                    var hist = new History();

                    hist.Number = int.Parse(item.ListView_No);
                    hist.a = double.Parse(item.ListView_a);
                    hist.b = double.Parse(item.ListView_b);
                    hist.c = double.Parse(item.ListView_c);
                    hist.Discriminant = double.Parse(item.ListView_Discriminant);
                    hist.x1 = item.ListView_x1;
                    hist.x2 = item.ListView_x2;
                    hist.dbDateTime = item.ListView_Datetime;

                    db.Histories.Add(hist);
                }
                db.SaveChanges();
            }
        }