组合不同长度的SQL查询

我想知道你将如何结合这两个查询

-- gets average sick leave for females for each job
SELECT AVG(SickLeaveHours) AS FSickLeave
FROM Employees
WHERE Gender = 'female'
GROUP BY Job
ORDER BY FSickLeave DESC;

-- gets average sick leave for males for each job
SELECT AVG(SickLeaveHours) AS MSickLeave
FROM Employees
WHERE Gender = 'male'
GROUP BY Job
ORDER BY MSickLeave DESC;

我已经尝试过使用子查询和联合，但由于列长度不同，所以遇到了问题

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感谢您的帮助。

关键是将条件放在

大小写表达式中，如果条件不匹配，请将值设置为
NULL
，以防止它成为
AVG
'd集合的一部分：

SELECT
    AVG(CASE WHEN Gender = 'female' THEN SickLeaveHours ELSE NULL END) AS FSickLeave,
    AVG(CASE WHEN Gender = 'male'   THEN SickLeaveHours ELSE NULL END) AS MSickLeave
FROM Employees
GROUP BY Job
ORDER BY FSickLeave DESC;

关键是将条件放在
CASE
表达式中，如果条件不匹配，则将值设置为
NULL
，以防止其成为
AVG
'd集合的一部分：

SELECT
    AVG(CASE WHEN Gender = 'female' THEN SickLeaveHours ELSE NULL END) AS FSickLeave,
    AVG(CASE WHEN Gender = 'male'   THEN SickLeaveHours ELSE NULL END) AS MSickLeave
FROM Employees
GROUP BY Job
ORDER BY FSickLeave DESC;

用户外部应用

SELECT AVG(SickLeaveHours) AS FSickLeave,MSickLeave
FROM Employees
OUTER APPLY(
SELECT AVG(SickLeaveHours) AS MSickLeave
FROM Employees
WHERE Gender = 'male'
GROUP BY Job
ORDER BY MSickLeave DESC
) M1
WHERE Gender = 'female'
GROUP BY Job
ORDER BY FSickLeave DESC;

用户外部应用

SELECT AVG(SickLeaveHours) AS FSickLeave,MSickLeave
FROM Employees
OUTER APPLY(
SELECT AVG(SickLeaveHours) AS MSickLeave
FROM Employees
WHERE Gender = 'male'
GROUP BY Job
ORDER BY MSickLeave DESC
) M1
WHERE Gender = 'female'
GROUP BY Job
ORDER BY FSickLeave DESC;

Case表达式，Case表达式。