Postgresql 如何将复杂的组转换为续集？

我的SQL查询是

SELECT t."id", t."topicText", COUNT(t."id") AS topicCount 
FROM "WorkbookQuestions" wq, "Workbooks" w, "Questions" q, "Topics" t 
WHERE  w."StudentId" = 3 
  AND wq."QuestionId" = q."id" 
  AND wq."WorkbookId" = w."id" 
  AND q."TopicId" = t."id"
GROUP BY "t"."id"
ORDER BY "topiccount" DESC

如何在

Sequelize

代码中编写此代码，以避免直接编写SQL？还是不可能

这是我迄今为止尝试过的（未成功的）：

---

只要看一下，我就会这样写代码

db.Workbook.findAll({
  attributes: ['wbquestion.question.topic.id', [db.sequelize.fn('COUNT', db.sequelize.col('wbquestion.question.topic.id'))], 'topiccount'],
  include: [
    {
      model: db.WorkbookQuestion,
            as: wbquestion,
      where: {
                id: wbquestion.workbookId      
            },
            include: [
                model: db.Question,
                as: question,
                where: {
                    id: wbquestion.questionId
                },
                include: [
                    model: db.Topic,
                    as: topic,
                    where: {
                        id: question.topicId
                    }
                ]
            ]
    }
  ],
    where: {
        studentId : 3
    }
  group: ['topic.id']
});

通过分别定义模型和关系并在之后使用即时加载，您可能可以获得更可读的代码

编辑： 生成迁移和模型

node_modules/.bin/sequelize model:create --name Student --attributes firstName:string,lastName:string
node_modules/.bin/sequelize model:create --name Topic --attributes topicText:string
node_modules/.bin/sequelize model:create --name Question --attributes TopicId:integer
node_modules/.bin/sequelize model:create --name Workbook --attributes studentId:integer
node_modules/.bin/sequelize model:create --name WorkbookQuestion --attributes QuestionId:integer,WorkbookId:integer

一个简单的程序，用于测试控制台日志中的查询

var Sequelize = require("sequelize");

var models = require('./models/index');

models.WorkbookQuestion.belongsTo(models.Question, {foreignKey: 'QuestionId'});
models.WorkbookQuestion.belongsTo(models.Workbook, {foreignKey: 'WorkbookId'});

models.Question.hasOne(models.WorkbookQuestion);

models.Workbook.hasOne(models.WorkbookQuestion);
models.Workbook.belongsToMany(models.Question, {through: models.WorkbookQuestion});
models.Workbook.belongsToMany(models.Topic, {through: models.Question});


var res = models.Workbook.findAll({
    attributes: ['topicId', Sequelize.fn('count', Sequelize.col('topiccount'))],
  include: [models.WorkbookQuestion, models.Question, models.Topic],
    where: {
        studentId: 3
    },
    group: ['topic.id']  
}).then(function(data) {
    console.log(data);
}).catch(function(err) {
    console.trace(err);
});

结果是：

SequelizeDatabaseError:列Topics.Question.WorkbookId不存在

---

也许您可以修复模型之间的关系，或者您应该不使用findAll功能创建查询。

有错误吗？Sequelize为您的示例生成的查询是什么样子的？

var Sequelize = require("sequelize");

var models = require('./models/index');

models.WorkbookQuestion.belongsTo(models.Question, {foreignKey: 'QuestionId'});
models.WorkbookQuestion.belongsTo(models.Workbook, {foreignKey: 'WorkbookId'});

models.Question.hasOne(models.WorkbookQuestion);

models.Workbook.hasOne(models.WorkbookQuestion);
models.Workbook.belongsToMany(models.Question, {through: models.WorkbookQuestion});
models.Workbook.belongsToMany(models.Topic, {through: models.Question});


var res = models.Workbook.findAll({
    attributes: ['topicId', Sequelize.fn('count', Sequelize.col('topiccount'))],
  include: [models.WorkbookQuestion, models.Question, models.Topic],
    where: {
        studentId: 3
    },
    group: ['topic.id']  
}).then(function(data) {
    console.log(data);
}).catch(function(err) {
    console.trace(err);
});