学习笔记-JDBC连接数据库操作的步骤

前言

这里我就以JDBC连接数据库操作查询的步骤作以演示，有不到之处敬请批评指正！

一、jdbc连接简要步骤

1.加载驱动器、
2.创建connection对象、
3.创建Statement对象、
4.Statement(executeQuery方法)执行sql语句、
5.创建处理结果集对象ResultSet、
6.处理异常，关闭所有JDBC对象资源(注意关闭顺序与声明顺序相反，先关结果集对象、后关statement对象、最后关connection对象)。

二、数据库表准备

/*
 Navicat Premium Data Transfer

 Source Server         : localhost-swp
 Source Server Type    : MySQL
 Source Server Version : 50730
 Source Host           : localhost:3306
 Source Schema         : project

 Target Server Type    : MySQL
 Target Server Version : 50730
 File Encoding         : 65001

 Date: 01/07/2022 16:36:16
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for sys_user
-- ----------------------------
DROP TABLE IF EXISTS `sys_user`;
CREATE TABLE `sys_user`  (
  `id` varchar(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '主键ID',
  `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '用户名',
  `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '密码',
  `nickname` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '昵称',
  `gender` int(1) DEFAULT 1 COMMENT '性别：0：女 1:男',
  `age` int(5) DEFAULT NULL COMMENT '年龄',
  `phone` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '联系电话',
  `status` int(1) DEFAULT 0 COMMENT '状态：0：正常  1：禁用',
  `birthday` date DEFAULT NULL COMMENT '生日',
  `remark` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '备注',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of sys_user
-- ----------------------------
INSERT INTO `sys_user` VALUES ('1', 'swp', '123456', '宋伟朋', 1, 28, '18740458584', 0, '1992-05-07', '备注信息');

SET FOREIGN_KEY_CHECKS = 1;

三、数据库操作代码编写

 public static void main(String[] args) throws Exception {

        Connection con = null;
        Statement statement = null;
        ResultSet rs = null;
        try {
            // 连接数据库url信息
            String url = "jdbc:mysql://localhost:3306/project?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&useSSL=false";
            // 用户名
            String username = "root";
            // 密码
            String password = "song@1234";

            // 1.加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 2.连接数据库相当于数据库
            con = DriverManager.getConnection(url, username, password);
            // 3.向数据库发送sql的对象 Statement
            statement = con.createStatement();
            // 4.编写sql
            String sql = "select * from sys_user";
            // 5.执行sql
            rs = statement.executeQuery(sql);

            while (rs.next()){
                System.out.println("id："+rs.getObject("id"));
                System.out.println("username："+rs.getObject("username"));
                System.out.println("password："+rs.getObject("password"));
                System.out.println("nickname："+rs.getObject("nickname"));
                System.out.println("gender："+rs.getObject("gender"));
                System.out.println("age："+rs.getObject("age"));
                System.out.println("phone："+rs.getObject("phone"));
                System.out.println("status:"+rs.getObject("status"));
                System.out.println("birthday："+rs.getObject("birthday"));
                System.out.println("remark："+rs.getObject("remark"));
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }finally {
            // 6.关闭连接，释放资源（一定要做） 先开后关
            rs.close();
            statement.close();
            con.close();
        }
    }

四、输出结果