另一个菜鸟问题;如何在这里实现Count（）？

Question

我有这个问题：

SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.*
FROM classified mt 
LEFT JOIN fordon ON fordon.classified_id = mt.classified_id 
LEFT JOIN boende ON boende.classified_id = mt.classified_id 
LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id 
LEFT JOIN business ON business.classified_id = mt.classified_id 
LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id 
LEFT JOIN hobby ON hobby.classified_id = mt.classified_id 
ORDER BY modify_date DESC

我需要在这里实现一个计数，只计算与你看到的JO​​INS组合的所有行。

我该怎么做？

SELECT COUNT(mt.*, fordon.* etc) FROM？ //这种方法不起作用

由于

Answer 1

我删除了ORDER BY，因为COUNT：

不需要

SELECT count(*)
FROM classified mt  
LEFT JOIN fordon ON fordon.classified_id = mt.classified_id  
LEFT JOIN boende ON boende.classified_id = mt.classified_id  
LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id  
LEFT JOIN business ON business.classified_id = mt.classified_id  
LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id  
LEFT JOIN hobby ON hobby.classified_id = mt.classified_id 

Answer 2

SELECT COUNT(*) FROM (SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*,     hem_inredning.*, hobby.*
FROM classified mt 
LEFT JOIN fordon ON fordon.classified_id = mt.classified_id 
LEFT JOIN boende ON boende.classified_id = mt.classified_id 
LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id 
LEFT JOIN business ON business.classified_id = mt.classified_id 
LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id 
LEFT JOIN hobby ON hobby.classified_id = mt.classified_id) As A

Answer 3

简单地说：

SELECT COUNT(*) FROM ...

Answer 4

SELECT COUNT(*) FROM ...怎么样？我不确定你在想什么。