private void butCF_Click(object sender, RoutedEventArgs e)        {            if (DatagridDatatable != null && DatagridDatatable.Rows.Count > 0)            {
//group by 日期,合同号,部门 having count(记录编号)>0    找出 日期 合同号 部门重复的记录                var query = (from t in DatagridDatatable.AsEnumerable()                            group t by new { t1 = t.Field<DateTime>("日期"), t2 = t.Field<Int64>("合同号"), t3 = t.Field<string>("部门") } into                            m                            select new                            {                                日期 = m.Key.t1,                                合同号 = m.Key.t2,                                部门 = m.Key.t3,                                记录编号=m.First().Field<Decimal>("记录编号"),//这里要写这句话，否则查不出query                                rowcount = m.Count()                            } into c where c.rowcount>1 select c).ToList();                DataTable dt = new DataTable();                ////dt.Columns.Add("序号",System.Type.GetType( "System.Int32"));                dt.Columns.Add("日期", System.Type.GetType("System.DateTime"));                dt.Columns.Add("合同号", System.Type.GetType("System.Int64"));                dt.Columns.Add("部门", System.Type.GetType("System.String"));                dt.Columns.Add("记录编号", System.Type.GetType("System.Decimal"));                dt.Columns.Add("销售金额", System.Type.GetType("System.Decimal"));                foreach (var q in query)                {                    DataRow[] dr_finds = DatagridDatatable.Select("日期=‘" + q.日期 + "‘ and 合同号=" + q.合同号 + " and 部门=‘" + q.部门+"‘");                    foreach (DataRow find in dr_finds)                    {                        DataRow dr = dt.NewRow();                        dr["日期"] = find["日期"];                        dr["合同号"] = find["合同号"];                        dr["部门"] = find["部门"];                        dr["记录编号"] = find["记录编号"];                        dr["销售金额"] = find["销售金额"];                        dt.Rows.Add(dr);                    }                }                if (dt.Rows.Count > 0)                {                   fmCFJL win=new  fmCFJL(dt);                   win.Show();                }                else                {                    MessageBox.Show("没有重复记录");                    return;                }            }        }