如何使用node.js控制sequelize中的内连接查询？答案

【问题标题】：How to control the inner join query in sequelize using node.js?如何使用node.js控制sequelize中的内连接查询？
【发布时间】：2019-04-22 05:13:52
【问题描述】：

天模型：

workoutId: {
    type: Sequelize.INTEGER,
},
traineeId: {
  type: Sequelize.INTEGER,
  primaryKey: true
},
dayNumber: {
  type: Sequelize.INTEGER,
  primaryKey: true
},
status: {
  type: Sequelize.INTEGER
},

WorkoutsExercises 模型：

workout_id: {
  type: Sequelize.INTEGER,
  primaryKey: true
},
exercise_name: {
  type: Sequelize.INTEGER,
  primaryKey: true
},
coach_id: {
  type: Sequelize.INTEGER,
  primaryKey: true
}

我只是想在两个表之间进行内部连接以返回每天的所有练习，我使用以下

const Days = require('../models/days');
const WorkoutsExercises = require('../models/workoutsExercises');

Days.findAll({
  include: [{
    model: WorkoutsExercises,
      required: true
   }]        
})

此函数返回以下查询：

SELECT
  `day`.`workoutId`,
  `day`.`dayNumber`,
  `day`.`status`,
  `day`.`traineeId`,
  
  `workoutsExercises`.`workout_id` AS `workoutsExercises.workout_id`, 
  `workoutsExercises`.`exercise_name` AS `workoutsExercises.exercise_name`, 
  `workoutsExercises`.`coach_id` AS `workoutsExercises.coach_id`

FROM `days` AS `day`

INNER JOIN `workoutsExercises` AS `workoutsExercises` 

ON `day`.`dayNumber` = `workoutsExercises`.`workout_id`;

如何将开启条件从 (day.dayNumber) 更改为 (day.workoutId)

【问题讨论】：

标签： node.js join sequelize.js inner-join

【解决方案1】：

如果您在两个模型之间有多个关系，您可以创建多个关联：

User.hasMany(Task);
Task.belongsTo(User);

User.hasMany(Task, {as: "secondAssociation", foreignKey, sourceKey});
Task.belongsTo(User, {as: "secondAssociation", foreignKey, targetKey});

您可以使用不同的 ON 子句运行此查询，该子句由您提供的用于创建关联的 foreignKey（和 sourceKey/targetKey）值确定：

User.findAll({
  include: [{
    model: Task
  }]

User.findAll({
  include: [{
    model: Task,
    as: "secondAssociation"
  }]
})

如果要更改给定查询的 ON 子句，可以使用 Model.findAll 方法的 include[].on 选项。

User.findAll({
  include: [{
    model: Task,
    on: {} //Use Sequelize.Op.col for reference on other column
  }]

【讨论】：

【解决方案2】：

关系应该如下

WorkoutExercises.hasMany(Day, {foreignKey: 'workout_id'})
Day.belongsTo(WorkoutExercises, {foreignKey: 'workout_id', targetKey: 'workout_id'})

目标键是改变 ON 子句的原因，我们将使用相同的查询：

Days.findAll({
  include: [{
    model: WorkoutsExercises,
    required: true
  }]        
})

给出：

SELECT

  `day`.`dayNumber`,
  `day`.`dayDate`,
  `day`.`status`,
  `day`.`traineeId`, 
  `day`.`workoutId`, 

  `workoutsExercises`.`exercise_name` AS `workoutsExercises.exercise_name`,
  `workoutsExercises`.`workout_id` AS `workoutsExercises.workout_id`,
  `workoutsExercises`.`coach_id` AS `workoutsExercises.coach_id`
 
 FROM `days` AS `day`
 
 INNER JOIN `workoutsExercises` AS `workoutsExercises`
 
 ON `day`.`workout_id` = `workoutsExercises`.`workout_id`;

【讨论】：