我正在尝试对多个条件进行计数并将它们作为单独的列返回答案

【问题标题】：I am trying to do counts on multiple conditions and get them back as separate columns我正在尝试对多个条件进行计数并将它们作为单独的列返回
【发布时间】：2021-05-06 01:00:42
【问题描述】：

SELECT * FROM
(SELECT COUNT("user_job".id) FROM "user_job" WHERE "user".job_title = 'Welder / Fitter') AS 
"WelderFitters"  
(SELECT COUNT("user_job".id)  AS "Welders"  FROM "user_job" WHERE "user".job_title = 
'Welder')
(SELECT COUNT("user_job".id)  AS "Fitters"  FROM "user_job" WHERE "user".job_title = 
'Fitter')
(SELECT COUNT("user_job".id)  AS "Helpers"  FROM "user_job" WHERE "user".job_title = 
'Helper')
JOIN "user" ON "user".id = "user_job".user_id 
JOIN "job" ON "job".id = "user_job".job_id
WHERE "job".id = 22;

//涉及两个连接。这根本不起作用，但我认为它说明了我正在尝试做的事情。

【问题讨论】：

听起来你可以使用GROUP BY "user".job_title。

标签： sql postgresql join count

【解决方案1】：

我认为您需要条件聚合。您的示例查询建议如下：

SELECT COUNT(*) FILTER (WHERE u.job_title = 'Welder / Fitter') AS 
"WelderFitters",
       COUNT(*) FILTER (WHERE u.job_title = 'Welder') AS 
"Welders",
       COUNT(*) FILTER (WHERE u.job_title =  'Fitter') AS "Fitters",
       COUNT(*) FILTER (WHERE u.job_title =  'Helper') AS "Helpers"
FROM "user" u JOIN
     "user_job" uj
     ON u.id = uj.user_id JOIN
     "job" j
     ON j.id = uj.job_id
WHERE j.id = 2;

但是，我不确定job_title 是否真的在users 表中。它似乎更有可能在jobs 表中。

【讨论】：

在 users 表中，非常感谢