本篇内容介绍了“node如何封装mysql处理语句”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

一.所需包

npm i mysql -S
npm i express -S

二.MySql连接文件

const mysql = require('mysql')function createConnection() {
    const connection = mysql.createConnection({
        host: '',  //地址
        user: '',  //用户名
        password: '',  //密码
        port: '',  //端口
        database: ''  //数据库名
    });
    return connection;}module.exports.createConnection = createConnection;

三.封装文件

引入MySQL连接相关文件，进行连接数据库操作

const mysql = require('../mysql/mysql')let connection = null;connection = mysql.createConnection();/**
 * 错误消息
 */let bad_msg = {
    code: 500,
    msg: '内部错误！'}/**
 * 成功消息
 */let success_msg = {
    code: 200,
    msg: '操作成功'}const connections = {
    /**
     * 查询方法
     * @param {*} table 表名
     * @param {*} condition 条件
     * @param {*} params 参数
     * @param {*} search 查询条件
     * @returns 
     */
    find(table, condition, params, search = '*') {
        return new Promise((resolve, reject) => {
            let sql = `SELECT ${search} FROM ${table} WHERE ${condition}`
            connection.query(sql, params, (err, result) => {
                if (err) {
                    reject(bad_msg)
                } else {
                    let _ = JSON.parse(JSON.stringify(success_msg))
                    _.data = result                    resolve(_)
                }
            })
        })
    },
    /**
     * 插入方法
     * @param {*} table 表名
     * @param {*} condition 条件
     * @param {*} params 参数
     * @returns 
     */
    insert(table, condition, params) {
        return new Promise((resolve, reject) => {
            const str = "?"
            let _ = str.repeat((condition.split(',')).length)
            let val = (Array.from(_)).toString()
            let sql = `INSERT INTO ${table}(${condition}) VALUES(${val})`
            connection.query(sql, params, (err, result) => {
                if (err) {
                    reject(bad_msg)
                } else {
                    resolve(success_msg)
                }
            })
        })
    },
    /**
     * 更新方法
     * @param {*} table 表名
     * @param {*} val 值
     * @param {*} condition 条件
     * @param {*} params 参数
     * @returns 
     */
    update(table, val, condition, params) {
        return new Promise((resolve, reject) => {
            let sql = `UPDATE ${table} SET ${val} WHERE ${condition}`
            connection.query(sql, params, (err, result) => {
                if (err) {
                    reject(bad_msg)
                } else {
                    resolve(success_msg)
                }
            })
        })
    },
    /**
     * 删除方法
     * @param {*} table 表名
     * @param {*} condition 条件
     * @param {*} params 参数
     * @returns 
     */
    del(table, condition, params) {
        return new Promise((resolve, reject) => {
            let sql = `DELETE FROM ${table} WHERE ${condition}`
            connection.query(sql, params, (err, result) => {
                if (err) {
                    reject(bad_msg)
                } else {
                    resolve(success_msg)
                }
            })
        })
    },}module.exports = connections

四.使用

我们使用登录注册来进行演示：

const express = require('express')const router = express.Router()const connections = require('../../static/connection')// token生成插件模块const jwt = require('jsonwebtoken');// Token签名var secret = ''const CreatId = require('../../static/ranId')router.post('/user/details', (req, res) => {
    connections.find('user_table', `ID=?`,req.user.ID).then(resp => {
        res.send(resp)
    })})router.post('/api/login', (req, res) => {
    connections.find('user_table', 'user=?', req.body.user).then(resp => {
        let {data} = resp        if (data.length !== 0) {
            for (let i = 0; i < data.length; i++) {
                // 邮箱或者密码不正确的时候
                if (req.body.user !== data[i].user || req.body.pwd !== data[i].pwd) {
                    res.send({
                        code: 202,
                        msg: '用户名或密码有误!'
                    })
                } else {
                    // 邮箱和密码输入正确
                    if (req.body.user === data[i].user && req.body.pwd === data[i].pwd) {
                        // 传输的token内容
                        let token = jwt.sign({ ID: data[i].ID }, secret, { expiresIn: '72H' });
                        // 返回结果
                        res.send({
                            code: 200,
                            msg: '操作成功！',
                            token: 'Bearer ' + token,
                        })
                    }
                }
            }
        } else {
            res.send({
                code: 400,
                msg: '账号不存在请注册!'
            })
        }
    }).catch(e => {
        res.send(e)
    })})router.post('/api/register', (req, res) => {
    connections.find('user_table', 'user=?', req.body.user).then(resp => {
        if (resp.data.length > 0) {
            res.send({
                code: 202,
                msg: '该用户已经存在！'
            })
        } else {
            let _ = req.body            let id = CreatId(3) + CreatId(3)
            connections.insert('user_table', 'ID,user,pwd,avatarUrl,location,RegisterTime,isAdmin,isDel', [id, _.user, _.pwd, '/static/userimg/user.webp', _.location, Date.now(), 0, 0]).then(resps => {
                // 传输的token内容
                let token = jwt.sign({ ID: id }, secret, { expiresIn: '72H' });
                // 返回结果
                res.send({
                    code: 200,
                    msg: '操作成功！',
                    token: 'Bearer ' + token,
                })
            })
        }
    })})module.exports = router