另一个菜鸟问题；如何在这里实现Count()? [英] Another rookie question; How to implement Count() here?

问题描述

我有这个查询:

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

我需要在此处实现一个计数，以便仅将所有行与您看到的JO​​INS结合起来计数.

I need to implement a count here, to just count all rows in combination with the JOINS you see.

我应该怎么做?

SELECT COUNT(mt.*，fordon.* etc)FROM 吗?//此方法无效

谢谢

推荐答案

我删除了 ORDER BY ，因为 COUNT 不需要它:

I removed the ORDER BY, as it is not required for the COUNT:

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 

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