我有三个MySQL表:
patient:
paID, paCode, paAccountID (foreign key)
test
tsID, tsName, tsPatientID (foreign key), tsAccountID (foreign key)
account
acID etc.
现在我想要统计与特定的 acID=1
相关联的 paID
和 tsID
的数量。有 6 个 tsID
和 4 个 paID
与 acID=1
相关联。
SELECT Count(paID) AS paCount FROM patient WHERE paAccountID=1
SELECT Count(tsID) AS tsCount FROM test WHERE tsAccountID=1
尝试将两者合并成一个查询...
SELECT Count(tsID) AS tsCount, Count(paID) AS paCount
FROM test LEFT JOIN patient ON tsPatientID = paID
WHERE tsAccountID=1
这样行不通,两个计数器都返回6。如何才能做到正确呢?