jdbc的知识

1. 现在既不需要

    Driver driver = new com.mysql.jdbc.Driver();
    DriverManager.registerDriver(driver);
   

   也不需要

   Class.forName("com.mysql.jdbc.Driver");
   

   使用下面的自动注册，wq是数据库的名称，前面是固定的

   String url = "jdbc:mysql://localhost:3306/wq";
   Connection connection = DriverManager.getConnection(url, "root", "1234");
   

2. 预防sql注入，使用prepareStatement;

   String url = "select * from wq where p_name = ? and p_type = ?";
   PreparedStatement preparedStatement = connection.prepareStatement(url);
   preparedStatement.setString(1, "vivo");
   preparedStatement.setInt(2, 2);
   

   sql注入：

   String url = "select * from wq where name = 'a' or 'a' = 'a' and password = 'a' or 'a' = 'a' ";