title: Java and MySQL insert statement
body: <p>I am just starting with JBDC. I need to create an Java/MySQL insert statement which inserts null, strings, and strings parsed to int (as an input from user using Scanner). I tried many possibilities and nothing is working so far. What would be the correct way of writing such an insert statement or maybe there is an other recommended way I should consider?
  Thanks for your help!</p>
  
  <pre><code>import java.util.ArrayList;
  import java.util.Scanner;
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  
  public class AddBook {
  
      static Scanner keyboard = new Scanner(System.in);
  
      static InvMenu invmenu = new InvMenu();
      static MainMenu mainmenu = new MainMenu();
  
      static boolean b = true;
      static int x;
      static double y;
      static double z;
      static String choice;
      static char letter;
  
      public static void addBook(){
  
          Connection conn = null;
          Statement stmt = null;
          ResultSet rs = null;
  
  
          System.out.println("+----------------+");
          System.out.println("| Add a Book     |");
          System.out.println("+----------------+\n");
  
          System.out.print("\nEnter ISBN number: "); 
          String isbn = keyboard.next();
  
          System.out.print("Enter Book Title: "); 
          String title = keyboard.next();
  
          System.out.print("Enter Author's name: "); 
          String author = keyboard.next();
  
          System.out.print("Enter Publisher's name: "); 
          String publisher = keyboard.next();
  
          System.out.print("Enter The Date the Book is Added to the Inventory (MM/DD/YYYY): "); 
          String dateAdded = keyboard.next();
  
          do{
  
              b = true;
              System.out.print("Enter The Quantity of Book Being Added: ");
              String qtyOnHand = keyboard.next();
  
              try {
  
                  x = Integer.parseInt(qtyOnHand);
  
              }
  
              catch(NumberFormatException nFE) {
  
                  b = false;
                  System.out.println();
                  System.out.println("--------------------------------------------------------");
                  System.out.println(" !!!   You did not enter a valid value. Try again   !!!");
                  System.out.println("--------------------------------------------------------");
                  System.out.println();
  
              }
  
          }while(b == false);
  
          do{
  
              b = true;
              System.out.print("Enter The Wholesale Cost of the Book: ");
              String wholesale = keyboard.next();
  
              try {
  
                  y = Double.parseDouble(wholesale);
  
              }
  
              catch(NumberFormatException nFE) {
  
                  b = false;
                  System.out.println("--------------------------------");
                  System.out.println(" !   Wrong Value. Try again   !");
                  System.out.println("--------------------------------\n");
  
              }
  
          }while(b == false);
  
          do{
  
              b = true;
              System.out.print("Enter The Retail Price of the Book: ");
              String retail = keyboard.next();
  
              try {
  
                  z = Double.parseDouble(retail);
  
              }
  
              catch(NumberFormatException nFE) {
  
                  b = false;
                  System.out.println("--------------------------------");
                  System.out.println(" !   Wrong Value. Try again   !");
                  System.out.println("--------------------------------\n");
  
              }
  
          }while(b == false);
  
          System.out.println("-------------------------------------------");
          System.out.println("ISBN number: " + isbn);
          System.out.println("Book Title: " + title);
          System.out.println("Author's name: " + author);
          System.out.println("Publisher's name: " + publisher);
          System.out.println("The Date the Book is Added to the Inventory (MM/DD/YYYY): " + dateAdded);
          System.out.println("The Quantity of Book Being Added: " + x);
          System.out.printf("The Wholesale Cost of the Book: $ %6.2f\n", y);
          System.out.printf("The Retail Price of the Book: $ %6.2f\n", z);
          System.out.println("-------------------------------------------\n");
  
          try {
  
              Class.forName("com.mysql.jdbc.Driver").newInstance();
  
              String connectionUrl = "jdbc:mysql://localhost:3306/serendipity";
              String connectionUser = "root";
              String connectionPassword = "password";
              conn = DriverManager.getConnection(connectionUrl, connectionUser, connectionPassword);
              stmt = conn.createStatement();
  
              stmt.executeUpdate("INSERT INTO books(book_id, isbn, title, author, publisher, dateAdded, qtyOnHand, wholesale, retail) VALUES ('"+null+ "','"  +isbn+ " ','" +title+ " ',' "  +author+ " ',' " +publisher+ " ',' " +dateAdded+ " ',' " +x+ " ',' " +y+ " ',' " +z+" ')");
  
  
          } 
  
          catch (Exception e) {
  
              e.printStackTrace();
  
          } 
  
          finally {
  
              try { 
  
                  if (rs != null) rs.close(); 
  
              } 
  
              catch (SQLException e) { 
  
                  e.printStackTrace(); 
  
              }
  
              try { 
  
                  if (stmt != null) stmt.close(); 
  
              } 
  
              catch (SQLException e) { 
  
                  e.printStackTrace(); 
  
              }
  
              try { 
  
                  if (conn != null) conn.close(); 
  
              } catch (SQLException e) { 
  
                  e.printStackTrace(); 
  
              }
  
                  System.out.println("+------------------------------------+");
                  System.out.println("| The Book is Added to the Inventory |");
                  System.out.println("+------------------------------------+\n"); 
  
          }
  
      }
  
  }
  </code></pre>