作为前端，我们无需去考虑数据库的问题，业务场景需要的话，我们可以mock数据，满足暂时的联调场景。但是对于数据库，我们前端可以不用，却不能不了解不懂。所以这篇文章整理下，nodejs框架express中怎么使用mysql这样的数据库。提升我们处理业务能力的水平！！！

安装mysql

1.硬安装，就是到mysql官网下载.exe安装包(window系统),mac自行百度哈
2.项目里面安装

npm i mysql

"dependencies": {"body-parser": "^1.20.2","cors": "^2.8.5","ejs": "^3.1.9","express": "^4.19.2","mysql": "^2.18.1"}

封装

const mysql = require("mysql");const db = mysql.createPool({host: "127.0.0.1",user: "root",password: "",database: "expressapp",
});module.exports = db;

database:数据库的名称，我们新建的表都放在这个库里，其他的字段见名知意

建库

这里大家可以选择图形化界面，也可以用cmd命令行，看个人习惯

我这里用的ideal自带的数据库可视化界面,大家可以自由发挥

联调开发

常见业务就是增删改查，所以我们分别来看看怎么在express里面操作

增

const db = require("../db/index");
//插入数据1const user = { username: "spider-man", password: "456789" };const sqlStr2 = "insert into tb_users (username,password) values (?,?)";db.query(sqlStr2, [user.username, user.password], (err, data) => {if (err) return console.log(err.message);if (data.affectedRows === 1) {console.log("插入成功");}
});//插入数据2  快速插入const user = { username: "hot-man", password: "987123" };const sqlStr2 = "insert into tb_users set ?";db.query(sqlStr2, user, (err, data) => {if (err) return console.log(err.message);if (data.affectedRows === 1) {console.log("插入成功");}
});

删

//删除数据，会真正删除数据,硬删除const sqlStr4 = "delete from tb_users where id = ?";db.query(sqlStr4, 7, (err, data) => {if (err) return console.log(err.message);if (data.affectedRows === 1) {console.log("删除成功");}});//标记删除，只是模拟删除，数据还在数据库,软删除
const sqlStr5 = "update tb_users set status = ? where id = ?";
db.query(sqlStr5, [1, 9], (err, data) => {if (err) return console.log(err.message);if (data.affectedRows === 1) {console.log("删除成功");}
});

改

//更新数据1const user = { id: 7, username: "aaa", password: "654321" };const sqlStr3 = "update tb_users set username = ? ,password = ? where id = ?";db.query(sqlStr3, [user.username, user.password, user.id], (err, data) => {if (err) return console.log(err.message);//执行update语句也是返回一个对象if (data.affectedRows === 1) {console.log("修改成功");}});//更新数据2--快捷方式const user = { id: 7, username: "sam1", password: "123456" };const sqlStr3 = "update tb_users set ? where id = ?";db.query(sqlStr3, [user, user.id], (err, data) => {if (err) return console.log(err.message);//执行update语句也是返回一个对象if (data.affectedRows === 1) {console.log("修改成功");}});

查

//查询数据const sqlStr = "select * from tb_users";db.query(sqlStr, (err, data) => {if (err) return console.log(err.message);console.log("🚀 ~ db.query ~ data:", data);});

一顿猛操作之后的数据库结果：

最后总结

列出下mysql数据库操作常见的命令行方式

show databases ;use expressapp;show tables ;//选择所有数据
select  * from tb_users;//选择特定字段的数据
select  id,username,status from  tb_users;//插入新数据
insert into tb_users  (username, password) values ('zs','11111'),('lusi','456123');
;//更新字段
update  tb_users set password='6565665',status = 1  where  id =  5;//删除记录
delete  from tb_users where  id = 4 or 5;select  * from tb_users where  id > 7;select  * from tb_users where  username != 'jack';select *
from tb_users where  id  = 7 or id =8;select  * from tb_users  order by  status desc, username asc;select  count(*) from tb_users where  status = 0;select count(*) as total  from tb_users;select username as user1,password  from tb_users;

这样，我们就在express这样的服务端框架里，实现了真实数据的处理，离大前端又近了一步！！^_