private void SearchStudent( )
        {
            if(readAll != null)
            {
                var query = from item in readAll
                            where item.name == SearchBox.Text
                            select item;

                if (query.Any())
                {
                    writeOne.Clear();
                    oneGridModel.Clear();
                    foreach (var item in query)
                    {
                        GridModel gm = new GridModel() { name = item.name
                        ,hms = item.hms
                        ,termId = item.termId
                        ,roomNum = item.roomNum
                        ,ymd = item.ymd};
                        //item.ymd.ToShortDateString()
                        WriteItem wi = new WriteItem() { ymd = item.ymd, hms = item.hms
                        , name = item.name, roomNum = item.roomNum, termId = item.termId };
                        writeOne.Add(wi);
                        oneGridModel.Add(gm);
                    }
                    IsSearch = true;
                    DG1.Items.SortDescriptions.Clear();
                    DG1.Items.SortDescriptions.Add(new SortDescription("roomNum", ListSortDirection.Ascending));
                }
            }
        }