A brief discussion on how nodejs connects to mysql database

This article will introduce to you how to use nodejs to connect to the mysql database. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Related recommendations: "nodejs tutorial"

1. Install the mysql module

npm install mysql

2. Create a general method

The Promise function callback is used here, you can not use it if you don’t need it

const mysql = require('mysql')	//引用mysql模块

//设置数据库基本信息
const pool = mysql.createPool({
    host:"localhost",	//IP
    user:"root",	//用户名
    password:"root",	//密码
    database:"heartsofiron"	//数据库名称
})

//创建通用方法,这里使用了Promise函数回调，如果不需要也可以不用的
const query = function(sql){
    return  new Promise(function(callback,errorback){
	    //连接数据库
        pool.getConnection(function(err,conn){	
            if(err){
            	//连接失败
                console.error(err)
            }else{
            	//连接成功
            	//连接成功之后执行sql语句,
            	//第一个参数sql就是语句,
            	//第二个参数是执行sql语句后的回调
                conn.query(sql,function(qerr,vals,fields){
                    conn.release()	//释放连接（关闭连接）
                    console.log(vals)
                    callback(vals)	//回调
                })
            }
        })
    })
}

module.exports = query	//输出

3. Use the above general function

query("select * from users").then(ret=>{
	//这里的ret就是查询后的结果
	console.log(ret)
})

Only the simplest method is shown here, but it can already meet the basic requirements In order to meet the needs of beginners and make it understandable, many additional plugins are not added.

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