[英]Where clause in left join using correlated query?
Here's the query: 这是查询:
SELECT c.Name As CompanyName, j.ID as JobID, j.Title as JobTitle,
ja.ApplicationDate, DATEDIFF(MONTH,ja.ApplicationDate, GETDATE()) AS MonthsAgo,
jsc.Name As Recruiter, js.Name As RecruitingAgency, jsh.Name As LastStatus
FROM Companies c
JOIN Jobs j
ON c.ID = j.CompanyID
JOIN JobApplications ja
ON j.ID = ja.JobID
LEFT JOIN JobContact jsc
ON jsc.ID = j.JobSourceContactID
LEFT JOIN JobContactCompany js
ON jsc.JobSourceCompanyID = js.ID
LEFT JOIN (
SELECT TOP 1 jh.JobID, jh.StatusDate, jt.Name
FROM JobStatusHistory jh
JOIN JobStatusTypes jt
ON jh.JobStatusTypeID = jt.ID
--WHERE jh.JobID = j.ID
ORDER BY jh.StatusDate DESC
) jsh
ON j.ID = jsh.JobID
ORDER BY ja.ApplicationDate
I'm trying to get the most recent job status for a particular job. 我正在努力获得特定工作的最新工作状态。 I can't figure out how to do the where clause (the commented WHERE) in the LEFT JOIN.
我无法弄清楚如何在LEFT JOIN中执行where子句(注释的WHERE)。 I've done this in the past, but can't remember how I did this in the past.
我过去做过这个,但不记得我过去是怎么做到的。
I will be grateful for any pointers. 我会感激任何指针。
You need to use OUTER APPLY . 您需要使用OUTER APPLY 。 A CROSS Apply is like an INNER JOIN where the applied table must return results, whereas an OUTER Apply is like a [LEFT] OUTER JOIN where the applied subquery may return no results.
CROSS Apply类似于INNER JOIN,其中应用的表必须返回结果,而OUTER Apply类似于[LEFT] OUTER JOIN,其中应用的子查询可能不返回任何结果。
SELECT c.Name As CompanyName, j.ID as JobID, j.Title as JobTitle,
ja.ApplicationDate, DATEDIFF(MONTH,ja.ApplicationDate, GETDATE()) AS MonthsAgo,
jsc.Name As Recruiter, js.Name As RecruitingAgency, jsh.Name As LastStatus
FROM Companies c
JOIN Jobs j ON c.ID = j.CompanyID
JOIN JobApplications ja ON j.ID = ja.JobID
LEFT JOIN JobContact jsc ON jsc.ID = j.JobSourceContactID
LEFT JOIN JobContactCompany js ON jsc.JobSourceCompanyID = js.ID
OUTER APPLY (
SELECT TOP 1 jh.JobID, jh.StatusDate, jt.Name
FROM JobStatusHistory jh
JOIN JobStatusTypes jt
ON jh.JobStatusTypeID = jt.ID
WHERE jh.JobID = j.ID
ORDER BY jh.StatusDate DESC
) jsh
ORDER BY ja.ApplicationDate
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