如何检查输入是否在数据库中？

Question

my JFrame cancels the ticket. I let the user input the ticket id which is stored in the database and phone number and that happened but my question is how can I check if this ticket is in a database or not ! please if you know

here is my code

 private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
  String Ticket_ID=CardNumberTF.getText();
    String phone=CardNumberTF1.getText();
 if(Ticket_ID.isEmpty()&& phone.isEmpty()){
 JOptionPane.showMessageDialog(null, "Please full the fields ");}

 else if(Ticket_ID.isEmpty() || phone.isEmpty()){
JOptionPane.showMessageDialog(null, "Please full the empty field  ");}

try{
 con=DriverManager.getConnection(URL,"iau","iau");
 prepared=con.prepareStatement("Delete from BOOKING_INFO WHERE ID_TICKET=? AND PHONE_NUM=?");
 prepared.setString(1,Ticket_ID );
 prepared.setString(2,phone );
 prepared.executeUpdate();
  JOptionPane.showMessageDialog(null,
 "deleted","delete",JOptionPane.PLAIN_MESSAGE);
       }catch(SQLException ex){
     JOptionPane.showMessageDialog(null, 
     "we don't have this ticket id", "Failed",JOptionPane.ERROR_MESSAGE);
       System.out.print(ex);
    }

 private void connect(){
        try{
            con=DriverManager.getConnection(URL, "iau","iau");
        }catch(SQLException ex){
            JOptionPane.showMessageDialog(null,ex);
        }}

Answer 1

Same as you are doing your delete statement prepared=con.prepareStatement("Delete from BOOKING_INFO WHERE ID_TICKET=? AND PHONE_NUM=?"); , for example:

boolean ticketExists = false;
prepared=con.prepareStatement("Select * BOOKING_INFO WHERE ID_TICKET=? AND PHONE_NUM=?");
prepared.setString(1, Ticket_ID);
prepared.setString(2, phone)

ResultSet result = prepared.executeQuery();

while (result.next()) {
   // this means that there is ticket, because the result is NOT NULL
   // set ticketExists to true
   ticketExists = true;
}

`