我如何获得每个城市的活动数量

Question

events表有一个名为“city_id”的列。我希望看到像这样的结果

Miami 30
Tampa 11
San Franciso 29

我正在使用mysql。

Answer 1

INNER JOIN，GROUP BY，COUNT ......这很有可能只需要你做这个简单的查询！

Answer 2

这样的事情会帮助你

SELECT 
  city_id,
  max(city_name),
  count(*)
FROM events
GROUP BY
  city_id

Answer 3

假设您在另一个表中有城市名称

select e.city_id, c.name, count(*) eventcount
from events e
join city c on c.id = e.city_id
group by e.city_id, c.name