循环多次汇总mysql

Question

对于我正在建设的报告工具，我希望能够计算出多少＆＃34;事件＆＃34;到目前为止已经记录的每个国家都有这个问题：

SELECT 'country',
      COUNT(*) AS total,
      SUM(CASE WHEN `country` = 'USA' THEN 1 ELSE 0 END) AS USCount,
      SUM(CASE WHEN `country` = 'Canada' THEN 1 ELSE 0 END) AS CanadaCount
  FROM events WHERE `date` > '2015-06-01' AND `date` < '2015-08-01'

唯一的问题是，当我开始将其他国家添加到组合中时，案例将开始变得庞大。有没有办法让我可以遍布各个国家/地区来检索每个国家/地区的所有各种计数？感谢。

Answer 1

尝试以下SQL语句：

Select country, count (*)
From events
Group by country

Answer 2

按国家/地区名称对其进行分组以明智地计算国家/地区

SELECT country,
  COUNT(*) AS total
 FROM events WHERE `date` > '2015-06-01' AND `date` < '2015-08-01' group by country;