01.if (comboBox5.SelectedIndex != -1)
02. {
03. command.CommandText = "select date_rental,date_rentalend,time_rental,time_rentalend from Lorry_rental where Lorry_id='" + comboBox5.Text + "' and date_rental <='" + dateTimePicker1.Text + "' and date_rentalend >='" + dateTimePicker3.Text + "' and time_rental <='" + comboBox6.Text + "' and time_rentalend >='" + comboBox7.Text + "' ";
04. command.Connection = conn;
05. conn.Open();
06. OdbcDataReader red = command.ExecuteReader();
07. if (red.HasRows)
08. {
09. red.Read();
10. MessageBox.Show("รถไม่ว่าง กรุณาเปลี่ยนรถคันใหม่ หรือ เปลี่ยนวันเวลาในการเช่า");
11. text5.Text = "";
12. comboBox5.Text = "";
13. comboBox5.Focus();
14. }
15. red.Close();
16. conn.Close();
17. }
