从表中获取计数的mysql查询
我有3张这样的桌子:从表中获取计数的mysql查询,mysql,Mysql,我有3张这样的桌子: Areas id city_id area 1 1 mayfield 2 2 cleveland neighbourhood id neighbourhood area_id 101 cayahoga 1 102 milan 1 103 downtown 2 Salons id
Areas
id city_id area
1 1 mayfield
2 2 cleveland
neighbourhood
id neighbourhood area_id
101 cayahoga 1
102 milan 1
103 downtown 2
Salons
id neighbourhood_id
3 101
4 101
5 102
我正在努力统计所有地区的所有沙龙
类似于区域内的沙龙(梅菲尔德=2,克利夫兰=1)
是否可以在1个查询中执行此操作 不给计数像:梅菲尔德2,克利夫兰1。它只是给count=3?不知道为什么那不起作用。我刚把它改成“count(s.id)”。。。现在应该可以工作了。。。
select area,count(s.id) as salon_count FROM
Areas a
INNER JOIN neighbourhood n
ON a.id = n.area_id
INNER JOIN
Salons s on s.neigbourhood_id = n.id
GROUP BY area
SELECT areas.area,COUNT(Salons.id)
FROM areas
LEFT JOIN neighbourhood ON neighbourhood.area_id = areas.id
LEFT JOIN Salons ON Salons.neighbourhood_id = neighbourhood.id
GROUP BY areas.id