knex.js 中的子查询或 knex.js 中使用原始或任何替代方式的直接 postgresql 查询答案

【问题标题】：Subquery in knex.js or direct postgresql queries in knex.js using raw or any alternative waysknex.js 中的子查询或 knex.js 中使用原始或任何替代方式的直接 postgresql 查询
【发布时间】：2019-06-02 05:07:22
【问题描述】：

我目前在 express.js 项目中工作，并使用 knex 进行数据库迁移和查询。我在编写查询以获得我在 postgresql (dbeaver) 中得到的确切结果时遇到了麻烦。下面给出了我需要转换为 knex 查询的查询（从表中）。实际上想要根据列的不同值（应用程序）获取列的计数

select count(job_id) as total_applicants ,

(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='qualified' and POS.creator_id='e5f604be-e773-490b- 
a525-fad3b95fd941') as qlCount,
(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='backup' and POS.creator_id='e5f604be-e773-490b-a525- 
fad3b95fd941') as bckCount,
(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='interview' and POS.creator_id='e5f604be-e773-490b- 
a525-fad3b95fd941') as intrCount,
(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='offer' and POS.creator_id='e5f604be-e773-490b-a525- 
fad3b95fd941') as offrCount,
(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='screening' and POS.creator_id='e5f604be-e773-490b- 
a525-fad3b95fd941') as screenCount,
(select count(job_id) from applications as APPL join 
recruiter_positions as POS on POS.position_id=APPL.job_id
where APPL.state='rejected' and POS.creator_id='e5f604be-e773-490b- 
a525-fad3b95fd941') as rejectedCount

from applications as APPL join recruiter_positions as POS on 
POS.position_id=APPL.job_id
where APPL.state notnull and POS.creator_id='e5f604be-e773-490b-a525- 
fad3b95fd941'

【问题讨论】：

欢迎来到 SO。由于您是新手，请查看How to Ask 和minimal reproducible example 部分。很抱歉，您的帖子中没有提供任何有用的信息，甚至没有提供任何实际问题。
我放在这里的查询在 postgresql 中按预期工作，只是想将其转换为 knex。实际上想根据列的不同值获取列的计数

标签： node.js database postgresql knex.js

【解决方案1】：

在不为您转换整个内容的情况下，下面是子查询在 Knex 中的工作方式。

每个查询都返回一个 Knex 查询构建器的实例，我们将其别名为 .as。所以逐步建立它们很容易：

const subquery1 = knex("foos").count("*").as("foocount");
const subquery2 = knex("bars").count("*").as("barcount");
knex.select(subquery1, subquery2).then(console.log);

【讨论】：