我想用Java Netbeans中的Mysql连接的正常程序将行插入MySql数据库，但当我运行此代码时，我的数据库不受影响。我已经设置了与Netbeans和Mysql的连接，它工作正常。
编码：

import java.sql.*;

    public class MySqlConnection {

       static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
       static final String DB_URL = "jdbc:mysql://localhost:3306/migration";
       static final String USER = "root";
       static final String PASS = "ngts12345";

       public static void main(String[] args) {

            Connection conn = null;

            try{
             Class.forName("com.mysql.jdbc.Driver");
             System.out.println("Connecting to a selected database...");
             conn = DriverManager.getConnection(DB_URL, USER, PASS);
             System.out.println("Connected database successfully...");
             System.out.println("Inserting records into the table...");

             String sql = "INSERT INTO document (document_id, document_name, format)" +
            "VALUES (?, ?, ?)";
             PreparedStatement preparedStatement = conn.prepareStatement(sql);
             preparedStatement.setInt(1, 1);
             preparedStatement.setString(2, "Test2");
             preparedStatement.setString(3, "Test3");
             preparedStatement.executeUpdate(); 
             preparedStatement.close();  
             conn.close();  
        }catch(SQLException se){
          //Handle errors for JDBC

       }catch(Exception e){
          //Handle errors for Class.forName

       }
     }
  }