JDBC API详解2

//stmt.executeUpdate 执行成功后，返回值为受影响行数，对DDL不能判断其0或1来断定是否执行成功

//ResultSet 
//stmt.executeQuery(sql):执行DQL语句，返回ResultSet对象


//获取查询结果
boolean next();//将光标移到下一行，并判断下一行是否为有效行
xxx getXxx(参数);//获取数据，xxx为数据类型，如：int getInt(参数);


import java.sql.*;
//获取表中的数据，并打印
public class JDBCdemo {
    public static void main(String[] args) throws Exception {
        //1.注册驱动
        Class.forName("com.mysql.cj.jdbc.Driver");

        //2.获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db1";
        String username = "root";
        String password = "1234";
        Connection conn = DriverManager.getConnection(url,username,password);

        //定义sql
        String sql = "select * from account";

        //获取statement对象
        Statement statement = conn.createStatement();

        //执行sql
        ResultSet rs = statement.executeQuery(sql);

        //处理结果
        while(rs.next()){
            int id = rs.getInt(1);
            String name = rs.getString(2);
            double money = rs.getDouble(3);
            System.out.println(id);
            System.out.println(name);
            System.out.println(money);
            System.out.println("===========================");
        }

        //释放资源
        rs.close();
        statement.close();
        conn.close();

    }

}