建表

MySQL程序可以使用PHP study集成工具。链接、操作数据库可以使用phpstudy自带的工具也可以使用navicat工具。

SQL语句-增删改查

  1. 插入数据

    insert into 表名(字段名1,字段名2) values(1,值2);

    例如:

    insert into user(name,description) values('陈浩南','铜锣湾扛把子');

    image-20200704162719944

  2. 删除数据

    delete from 表名 where 条件;

    条件一定要写,如果不写则会删除该表中所有的数据删除。

    例如:

    delete from user where id>3;
  3. 修改数据

    update 表名 set 字段名1=新值1,字段名2=新值2 where 条件;

    条件一定要写,如果不写则会修改数据表中的全部数据

    例如:

    update user set name='子风兄',description='比波波还骚' where id=3;
  4. 查询数据

    select * from 表名 [where 条件];

    image-20200704164131234

NodeJs操作数据库

NodeJs链接数据库需要使用模块mysql。基本结构如下:

var mysql = require("mysql");
// 创建一个链接数据库的链接
var connection = mysql.createConnection({
    // 数据库地址
    host: "localhost",
    // 数据库账号
    user: "root",
    // 数据库密码
    password: "root",
    // 数据库名(非表名)
    database: "study",
});
// 打开链接
connection.connect();

// 具体语句
// .....

connection.end();

连接与关闭链接可以不写。

connection.query("select * from user", (error, result, fields) => {
  // 如果查询遇到错误,则error代表错误。没有错误则为null
  console.log(error);
  // 执行sql语句得到的结果。如果查询遇到错误,则为undefined
  console.log(result);
  // 字段信息
  console.log(fields);
});

result

image-20200704170616466

fields

image-20200704170635370

其他查询方法

  1. 以什么开头

    select * from hero where heroName like "马%";

    image-20200706192609590

  2. 以什么结尾

    select * from hero where heroName like "%韦";

    image-20200706192724093

  3. 包含什么内容

    select * from hero where heroName like "%魔%";

    image-20200706192800250

  4. 并且条件

    select * from hero where heroName like "%魔%" and isDelete='false';

    可用and链接多个条件。

    image-20200706193125673

  5. 或条件

    select * from hero where heroName like "%魔%" or heroName like "%信%";

    image-20200706193321722

  6. 排序

    • 降序

      select * from hero where heroName like "%魔%" or heroName like "%信%" order by id desc;

      image-20200706193441568

    • 升序

      默认为升序

      select * from hero where heroName like "%魔%" or heroName like "%信%" order by id asc;

      image-20200706193535578

    • 分页

      倒序情况下拿到前20条数据

      select * from hero  order by id desc limit 0,20;

      image-20200706193830578

    • 连表查询

      select 字段 from1 inner join2 on 对应关系
      select * from horder inner join customer on horder.cid = custom.id;

      可对两个表设置别名,但是后边也要设置别名。

      select * from horder h inner join customer c on h.cid = c.id;

      也可以只查询某个字段。

      select h.id,h.oname,c.price,c.id,c.cname,c.age from horder h inner join customer c on h.cid = c.id;

let name = "伦哥";
let description = "这是个描述";
connection.query(
    `insert into user(name,description) values('${name}','${description}')`,
    (error, result, fields) => {
        // 如果查询遇到错误,则error代表错误。没有错误则为null
        console.log(error);
        // 执行sql语句得到的结果。如果查询遇到错误,则为undefined
        console.log(result);
        // 字段信息
        console.log(fields);
    }
);

其中result会返回一个对象,fields返回undefined。其中affectedRows表示受影响的行数,如果大于0则表示新增成功。

image-20200704171121849

let id = 3;
connection.query(`delete from user where id=${id}`, (error, result, fields) => {
    if (error == null) {
        console.log(result);
    }
});

image-20200704172128720

改与新增类似。

let name = "伦哥";
let description = "这是个描述";
let id = 3;
connection.query(
    `update user set name='${name}',description='${description}' where id=${id}`,
    (error, result, fields) => {
        if (error == null) {
            console.log(result);
        }
    }
);

image-20200704171859547

英雄管理系统-添加接口

app.post("/hero/add", upload.single("heroIcon"), (req, res) => {
  // 1.1 接收前端传递过来的参数
  console.log(req.file);
  console.log(req.body);
  let heroIcon = req.file.filename;
  let { heroName, heroSkill } = req.body;
  // 执行sql语句代码
  connection.query(
    `insert into hero(heroName,heroSkill,heroIcon) values('${heroName}','${heroSkill}','${heroIcon}');`,
    (error, result, fields) => {
      if (error == null) {
        res.send({
          code: 200,
          msg: "新增成功",
          list: { heroName: heroName, heroSkill: heroSkill },
        });
      } else {
        res.send({
          code: 400,
          msg: "新增失败",
          list: { heroName: heroName, heroSkill: heroSkill },
        });
      }
    }
  );
});

英雄管理系统-获取接口

app.get("/hero/all", (req, res) => {
    connection.query(
        `select id,heroName,heroSkill,heroIcon from hero where isDelete = 0`,
        (error, result, fields) => {
            if (error == null) {
                console.log(result);

                res.send({
                    code: 200,
                    msg: "查询成功",
                    list: result,
                });
            } else {
                res.send({
                    code: 400,
                    msg: "查询失败",
                    list: null,
                });
            }
        }
    );
});

完整代码

const express = require("express");
const multer = require("multer");
const mysql = require("mysql");

var connection = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: "root",
    database: "study",
});

const app = express();
var upload = multer({ dest: "uploads/" });
app.use(express.static("uploads"));
// 路由
// 参数:heroName heroSkill,heroIcon(文件),
app.post("/hero/add", upload.single("heroIcon"), (req, res) => {
    // 1.1 接收前端传递过来的参数
    console.log(req.file);
    console.log(req.body);
    let heroIcon = req.file.filename;
    let { heroName, heroSkill } = req.body;
    // 执行sql语句代码
    connection.query(
        `insert into hero(heroName,heroSkill,heroIcon) values('${heroName}','${heroSkill}','${heroIcon}');`,
        (error, result, fields) => {
            if (error == null) {
                res.send({
                    code: 200,
                    msg: "新增成功",
                    list: { heroName: heroName, heroSkill: heroSkill },
                });
            } else {
                res.send({
                    code: 400,
                    msg: "新增失败",
                    list: { heroName: heroName, heroSkill: heroSkill },
                });
            }
        }
    );
});

app.get("/hero/all", (req, res) => {
    connection.query(
        `select id,heroName,heroSkill,heroIcon from hero where isDelete = 0`,
        (error, result, fields) => {
            if (error == null) {
                console.log(result);

                res.send({
                    code: 200,
                    msg: "查询成功",
                    list: result,
                });
            } else {
                res.send({
                    code: 400,
                    msg: "查询失败",
                    list: null,
                });
            }
        }
    );
});

// 开启服务器
app.listen(3000, () => {
    console.log("开启成功");
});