private void txtUsername_TextChanged(object sender, EventArgs e) { string staffID = (string)dtgvAccount.SelectedCells[0].OwningRow.Cells["Mã nhân viên"].Value; Staff staff = StaffDAO.GetStaffByID(staffID);//The staff that we're currently selecting if (staff == null) { //The case that nothing on dtgv - no result after searched return; } cboStaffID_Account.SelectedItem = staff; int index = -1; int i = 0; foreach (Staff item in cboStaffID_Account.Items) { if (item.ID == staff.ID) { index = i; break; } i++; } cboStaffID_Account.SelectedIndex = index; }