任何人都可以纠正sql查询吗？

Question

我需要城市和空缺的数量，在这个城市的工作。城市，简历，空缺 - 表。

下面是一个查询我写的，但它不工作（第二LEFT JOIN不工作）

SELECT c.name city_name, 
COUNT(v.id) vac_num, (r.id) res_num 
FROM mnk_city c 
LEFT JOIN mnk_vacancy 
ON v.cityId = c.id 
LEFT JOIN mnk_resume 
ON c.id = r.cityId 
GROUP BY c.name 

Answer 1

SELECT c.name city_name, 
COUNT(v.id) vac_num, (r.id) res_num 
FROM mnk_city c 
LEFT JOIN mnk_vacancy v 
ON v.cityId = c.id 
LEFT JOIN mnk_resume r 
ON c.id = r.cityId 
GROUP BY c.name 

你缺少了表的别名。

Answer 2

看来你错过了一些表别名 - mnk_vacancy应该跟着v，据我所知，mnk_resume应该跟着r。

SELECT c.name city_name, 
COUNT(v.id) vac_num, (r.id) res_num 
FROM mnk_city c 
LEFT JOIN mnk_vacancy v 
ON v.cityId = c.id 
LEFT JOIN mnk_resume r 
ON c.id = r.cityId 
GROUP BY c.name