private void btnSearch_Click(object sender, EventArgs e) { string pid = ""; string process = ""; if (cboProduct.SelectedIndex > 0) { pid = cboProduct.SelectedValue.ToString(); } if (cboProcess.SelectedIndex > 0) { process = cboProcess.Text; } try { PerformanceService service = new PerformanceService(); perList = service.SearchPerList(pid, process); string FromDate = periodSearchControl.dtFrom; string ToDate = periodSearchControl.dtTo; List <PerformanceVO> PerformanceList = (from per in perList where Convert.ToDateTime(FromDate) <= Convert.ToDateTime(per.production_sdate) && Convert.ToDateTime(per.production_sdate) <= Convert.ToDateTime(ToDate) select per).ToList(); dgvPerformance.DataSource = PerformanceList; } catch (Exception err) { MessageBox.Show(err.Message); } }