2阶——JDBC

package cn.jdbc;

import com.mysql.jdbc.Driver;

import java.sql.*;

public class Demo1 {
    public static void main(String[] args) {

        String url = "jdbc:mysql://localhost:3306/day11";
        String username = "root";
        String password = "123456";
        
        try {
            Class.forName("com.mysql.jdbc.Driver"); //将Driver类加载到内存 就会自动执行以下的静态代码块

           // com.mysql.jdbc.Driver 通过查看源码Driver中含有以下静态代码块
//            static {
//                try {
//                    DriverManager.registerDriver(new Driver());
//                } catch (SQLException var1) {
//                    throw new RuntimeException("Can‘t register driver!");
//                }
//            }

            
            Connection cn = DriverManager.getConnection(url,username,password);

            String sql = "select * from day11";

            PreparedStatement sta = cn.prepareStatement(sql);
            ResultSet rs = sta.executeQuery();

            while (rs.next()){
                int id = rs.getInt(1);
                String name = rs.getString(2);
                System.out.println(id+"___"+name);
            }


            rs.close();
            sta.close();
            cn.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}