数据库教程:sequelize的简单使用（增、删、查、改）

一、说明

使用的是mysql数据库，数据库叫做koa2_weibo_db，其中一共有2张表，一张blogs表，一张users表

• blogs
  

• users
  

二、安装

npm i mysql2 sequelize -d  

三、创建连接

const Sequelize = require('sequelize') const conf = {     host:'localhost',     dialect:'mysql' } const seq = new Sequelize('koa2_weibo_db','root','root',conf) module.exports = seq 

四、创建模型

//引入模块 const Sequelize = require('sequelize') const seq = require('./seq')  //创建 User 模型。数据表的免费精选名字大全是users const  User  = seq.define('user',{     //id会自动创建，并且自动递增     userName:{         type:Sequelize.STRING,//vachar(255)         allowNull:false     },     password:{         type:Sequelize.STRING,//vachar(255)         allowNull:false     },     nickName:{         type:Sequelize.STRING,         commit:'免费精选名字大全'     } })  //创建 Blog 模型。数据表的免费精选名字大全是blogs const  Blog  = seq.define('blogs',{     //id会自动创建，并且自动递增     title:{         type:Sequelize.STRING,//vachar(255)         allowNull:false     },     content:{         type:Sequelize.TEXT,         allowNull:false     },     userId:{         type:Sequelize.INTEGER,         allowNull:false     } }) module.exports = {     User,     Blog } 

五、增加

 const { Blog, User } = require('./mode')    !(async function(){      //创建用户      const zhangsan = await User.create({          userName:'zhangsan',          password:'123',          nickName:'张三'      })      const zhangsanId = zhangsan.dataValues.id       console.log('zhangshan:',zhangsan.dataValues)       const lisi = await User.create({         userName:'lisi',         password:'123',         nickName:'李四'     })     const lisiId = lisi.dataValues.id      const blog1 = await Blog.create({         title:'标题1',         content:'内容1',         userId:zhangsanId     })     const blog2 = await Blog.create({         title:'标题2',         content:'内容2',         userId:zhangsanId     })     const blog3 = await Blog.create({         title:'标题3',         content:'内容3',         userId:lisiId     })     const blog4 = await Blog.create({         title:'标题4',         content:'内容4',         userId:lisiId     })  })() 

六、删除

const { User, Blog} = require('./mode')  !(async function(){     const destroyRes = await User.destroy({         where:{             id:2         }     })     console.log('destroy......',destroyRes) })() 

七、查找

const { Blog, User } = require('./mode')   !(async function(){     一条记录     const zhangsan = await User.findOne({         where:{             userName:'zhangsan'         }     })     console.log('zhangsan:',zhangsan.dataValues)          查询特定的列     const zhangsanName = await User.findOne({         attributes:['userName','nickName'],         where:{             userName:'zhangsan'         }     })     console.log('zhangsanName:',zhangsanName.dataValues)      查询一个列表     const zhangsanBlogList = await Blog.findAll({         where:{             userId:1         },         order:[             ['id','desc']         ]     })     console.log('zhangsanBlogList:',zhangsanBlogList.map(blog => blog.dataValues))      分页     const blogPageList = await Blog.findAll({         limit:2,         offset:0,         order:[             ['id','desc']         ]     })     console.log('zhangsanBlogList:',blogPageList.map(blog => blog.dataValues))      查询总数     const blogListAndCount = await Blog.findAndCountAll({         limit:2,         offset:0,         order:[             ['id','desc']         ]     })     console.log(blogListAndCount.count)     console.log('..............................................')     console.log(blogListAndCount.rows.map(blog => blog.dataValues)) })() 

八、更改

const { User } = require('./mode')  !(async function(){     const updateRes = await User.update({         nickName:'张三'     },{         where:{             userName:'zhangsan'         }     })     console.log('updating......',updateRes) })() 

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