JDBC.rar_adultieu_birthday6v4_数据库jdbc

package com.bwf3; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Timestamp; import java.util.ArrayList; import java.util.Date; public class Demo1 { /* MYSQL 属于 关系-对象型 数据库 表 ---- 类 student --- 学生类 列属性 --- 类的成员属性 sid sname sage stime 行数据 ---- 对象 4 | dd | 12 | 2018-01-01 10:20:52 | ---- new Student(4,"dd",12,Date) 一张表 ---- 实体类 保证类的属性 ---- 表的属性 (类型) */ public static void main(String[] args) throws ClassNotFoundException, SQLException { //新增不需要id // Student s = new Student("h", 10, new Date()); // addStu(s); //修改的时候 需要id // Student s = new Student(6,"ff", 14, new Date()); // updateStu(s); // ArrayList<Student> list = queryStuAll(); // // for(Student s: list){ // System.out.println(s); // } System.out.println(queryStuOne(9)); System.out.println(queryStuOne(100)); } //查询一个学生 返回学生对象 查询到 返回对象 没查询到 返回null public static Student queryStuOne(int id) throws ClassNotFoundException, SQLException{ //返回值 Student s = null; //驱动 Class.forName("com.mysql.jdbc.Driver"); //连接 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","123"); //sql语句 String sql = "select * from student where sid = ?"; //预处理 PreparedStatement ps = conn.prepareStatement(sql); //赋值 ps.setInt(1, id); //获得数据集 ResultSet rs = ps.executeQuery(); if(rs.next()){ s = new Student();//查询到 才初始化 s.id = rs.getInt("sid"); s.name = rs.getString("sname"); s.age = rs.getInt("sage"); s.time = rs.getTimestamp("stime"); } return s; } //查询所有行数据 ---- 学生 ---- 返回集合 ArrayList<Student> public static ArrayList<Student> queryStuAll() throws ClassNotFoundException, SQLException{ //返回值 默认size = 0 ArrayList<Student> list = new ArrayList<Student>(); //驱动 Class.forName("com.mysql.jdbc.Driver"); //连接 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","123"); //sql语句 String sql = "select * from student"; //预处理 PreparedStatement ps = conn.prepareStatement(sql); //获得数据集 ResultSet rs = ps.executeQuery(); Student s = null; //[0x01,0x01,0x01,0x01] //每一行数据 ----- 一个对象 while(rs.next()){ s = new Student();//0x01 s.id = rs.getInt("sid"); s.name = rs.getString("sname"); s.age = rs.getInt("sage"); //java.util.Date 父类 ----- Timestamp 子类 多态 s.time = rs.getTimestamp("stime"); list.add(s); } return list; } //修改 6 | f | 14 | 2018-01-01 10:20:54 | ---- 6 | ff | 14 | 2018-01-01 10:20:54 | //把修改后的信息 组成一个对象 变的就变了 不变的就不变 public static void updateStu(Student stu) throws ClassNotFoundException, SQLException{ //驱动 Class.forName("com.mysql.jdbc.Driver"); //连接 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","123"); //sql语句 String sql = "update student set sname = ?,sage = ?,stime = ? where sid = ?"; //预处理 PreparedStatement ps = conn.prepareStatement(sql); //赋值 ps.setString(1, stu.name); ps.setInt(2, stu.age); ps.setTimestamp(3, new Timestamp(stu.time.getTime())); ps.setInt(4, stu.id); //同步执行 int row = ps.executeUpdate(); System.out.println(row>0 ? "更新成功":"更新失败"); } //增加行数据 ---- 把要增加的行数据信息封装到一个对象中 把对象当做参数 public static void addStu(Student stu) throws ClassNotFoundException, SQLException{ //驱动 Class.forName("com.mysql.jdbc.Driver"); //连接 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","123"); //sql语句 String sql = "insert into student (sname,sage,stime) values(?,?,?)"; //预处理对象 PreparedStatement ps = conn.prepareStatement(sql); //赋值 要插入的一行信息 都在stu中 id依靠自增 ps.setString(1, stu.name); ps.setInt(2, stu.age); ps.setTimestamp(3, new Timestamp(stu.time.getTime())); //同步执行 int row = ps.executeUpdate(); System.out.println(row>0 ? "插入成功":"插入失败"); //关闭 if(ps!=null){ ps.close(); } if(conn!=null){ conn.close(); } } }