Databases - SQL | 易学教程

Connect app to SQL database

 npm install --save mysql2

 const mysql = require('mysql2');  // connection pool // manage multiple connections (multiple queries) simultaneously. const pool = mysql.createPool({     host: 'localhost',     user: 'root',     database: 'node-complete',     password:'Meiting5' });  module.exports = pool.promise();

execute sql queries

 db.execute('')

Sequelize

An object-relational mapping library

sequelize works with Promises

it does all the heavy lifting, all the SQL code behind the scenes for us and maps it into javascript objects with convenience methods which we can call to execute that behind the scenes SQL code so that we never have to write SQL code on our own.

 npm install --save sequelize

 const Sequelize = require("sequelize");  const sequelize = new Sequelize("node-complete", "root", "Meiting5", {   dialect: "mysql",   host: "localhost" });  module.exports = sequelize;

define model

 const Product = sequelize.define('product',{   id: {     type:Sequelize.INTEGER,     autoIncrement: true,     allowNull: false,     primaryKey: true   },   title: Sequelize.STRING,    price:{     type: Sequelize.DOUBLE,     allowNull: false   },   imageUrl: {     type: Sequelize.STRING,     allowNull: false   },   description: {     type: Sequelize.STRING,     allowNull: false   } });

Create table

 sequelize   .sync()   .then(result => {     app.listen(3000);   })   .catch(err => {     console.log(err);   });

Insert Data & create a product

 exports.postAddProduct = (req, res, next) => {   const title = req.body.title;   const imageUrl = req.body.imageUrl;   const price = req.body.price;   const description = req.body.description;   Product.create({     title: title,     price: price,     imageUrl: imageUrl,     description: description   })     .then(result => {       console.log("Created Product");     })     .catch(err => {       console.log(err);     }); };

Retrieving data and find products

 Product.findAll()    .then(products => {       res.render("shop/index", {         prods: products,         pageTitle: "Shop",         path: "/"       });     })     .catch(err => console.log(err));

 // Product.findAll({where: {id: prodId}})  Product.findByPk(prodId)     .then((product) => {       res.render("shop/product-detail", {         product: product,         pageTitle: product.title,         path: "/products"       });     })     .catch(err => console.log(err));

 // create if not exist, overwrite if not exist product.save();

delete

 Product.findByPk(prodId)     .then(product => {       return product.destroy();     })     .then(result => {       console.log("DESTROYED");       res.redirect("/admin/products");     })     .catch(err => console.log(err));

 // delete user, all product associated to the user gone Product.belongsTo(User,{constraints: true, onDelete: 'CASCADE'}); User.hasOne(Cart);

create new associated object

 // pass data cannot be inferred by sequelize req.user.createProduct({     title: title,     price: price,     imageUrl: imageUrl,     description: description   })

 .getProducts()

来源：51CTO

作者：fwu11

链接：https://blog.csdn.net/weixin_42552135/article/details/100691233

标签

sequelize