计算属于特定类型的条目

Question

假设我有一个名为people的数据库：

有id和type

我如何计算 属于特定类型的人。

我不想要像这样的查询，我想自动执行此操作：

SELECT 
         COUNT(CASE WHEN type = 'single' THEN 1 END) as single,
         COUNT(CASE WHEN type = 'married' THEN 1 END) as marrried,
         COUNT(CASE WHEN type = 'kids' THEN 1 END) as kids
         ......
FROM people;

我该怎么做？致谢

Answer 1

使用分组

SELECT COUNT(id), type FROM people GROUP BY  type

Answer 2

与你的最接近的技巧是：

  SELECT
   SUM(CASE WHEN type = 'single' THEN 1 ELSE 0 END) as single,
   SUM(CASE WHEN type = 'married' THEN 1 ELSE 0 END) as marrried,
  ...