如果找不到记录，MySQL计数返回零 [英] Mysql count return Zero if no record found

问题描述

我有两个桌子.

cities - id_city, city_name
properties - id_property, id_city, property_name

我要显示cities.city_name并在其旁边显示[properties.count(id_city)]

I want to display cities.city_name and next to it [properties.count(id_city)]

如果没有找到任何记录而不是NULL，如何进行查询仍返回零的查询，这样我将得到如下结果:

How do I make a query that still returns zero if no records are found instead of NULL, so that I get results like this:

London [123]
New York [0]
Berlin [11]

其中纽约"是[0]，而不是NULL而不是1?

where "New York" is [0], not NULL and not 1?

推荐答案

使用外部联接:

select cities.city_name, count(properties.id_city)
  from cities left join properties on cities.id_city = properties.id_city
  group by 1

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