mysql - 如何对值为 X 的列执行计数

Question

有没有一种方法可以使用 SQL 执行计数操作，其中列等于 X，理想情况下，当同一列等于 Y 和 Z 时，单独计数？

Answer 1

SELECT yourcolumn, COUNT(*) AS cnt
FROM yourtable
WHERE yourcolumn IN ('X', 'Y', 'Z')
GROUP BY yourcolumn

Answer 2

像这样的东西？

select
  sum(case when val = 'x' then 1 else 0 end) as countX
  ,sum(case when val = 'y' then 1 else 0 end) as countY
  ,sum(case when val = 'z' then 1 else 0 end) as countZ 
from table

Answer 3

我建议如下：

SELECT YourColumn, COUNT(<Any Column of your table>)
FROM YourTable
GROUP BY YourColumn

Answer 4

我相信以下（较短的）语句应该适用于 MySQL：

SELECT COUNT(val='X'), COUNT(val='Y'), COUNT(val='Z') FROM ...