Question

RDBMS和Sequelize的新手也希望在JOINS中获得更多内容。我不知道如何通过SEQUELIZE执行JOINS。我有3个表USERS，ORDERS，PRODUCTS ORDERS表包含USERS，PRODUCTS主键作为其外键。我在下面附上我的型号代码用户模型

const Sequelize = require('sequelize');
const sequelize = require('../config');
let Users = sequelize.define('users', {
  id : {
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true
  },
  username: {
    type: Sequelize.STRING,
  },
  password: {
    type: Sequelize.STRING
  }
});
module.exports = Users;

产品型号

const Sequelize = require('sequelize');
const sequelize = require('../config');
let products=sequelize.define('products', {
  id : {
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true
  },
  category : {
    type: Sequelize.STRING,
    allowNull: false
  },
  name : {
    type: Sequelize.STRING,
    allowNull: false
  },
  price: {
    type: Sequelize.INTEGER,
    allowNull: false
  }
});
module.exports= products;

订单模型

const Sequelize = require('sequelize');
const sequelize = require('../config');
let users=require('./user');
let products=require('./product');
let orders=sequelize.define('orders', {
  id: {
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true
  },
  user_id: {
    type: Sequelize.INTEGER,
    references: {
        model: 'users',
        key: 'id'
    }
  },
  product_id: {
    type: Sequelize.INTEGER,
    references: {
        model: 'products',
        key: 'id'
    }
  },
  price: {
    type: Sequelize.INTEGER,
    allowNull: false
  }
});
module.exports= orders;

我希望通过SEQUELIZE

执行以下原始查询

SELECT * FROM ((orders INNER JOIN users ON users.id=orders.user_id) INNER JOIN products ON products.id=orders.product_id);

我查看了文档，但我无法弄清楚如何做到这一点。非常感谢。谢谢

Answer 1

您需要做的第一件事就是设置Associations。

所以让我们把它分解成部分。我们知道您的ORDERS表包含USER和PRODUCT的ID。这就是为这些表设置关联的方法。

我假设用户有很多订单。我们在两个方向上建立联系。

User.hasMany（Orders，{foreignKey：'user_id'}）; Order.belongsTo（User，{foreignKey：'user_id'}）;

您似乎正确定义了模型。

现在为了进行连接，在设置关联之后，我们想要设置一个查询来为表做连接。现在请记住，这将在您的控制器中完成。

//确保您在此处导入模型以使用

export function getRequestsByWeek(req, res) {
  return order.findAll({
    include: [
      {model: users, attributes: []}, // nothing in attributes here in order to not import columns from users
      {model: products} // nothing in attributes here in order to not import columns from products
    ],
    attributes: ['id'], //in quotes specify what columns you want, otherwise you will pull them all
    // Otherwise remove attributes above this line to import everything. 
  })
    .then(respondWithResult(res))
    .catch(handleError(res));
}

如何在Sequelize Postgresql中执行多个内部联接

2 个答案: