mysql - 我想根据 where 子句在不同列上显示一列数据总和

Question

下面是描述我的要求的图片我有一个包含不同数据的列我希望它在数据= 1作为col1和数据= 2作为col2的条件下计数等等....

Answer 1

SELECT
  COUNT(CASE data WHEN 1 THEN 1 ELSE NULL END) as Col1,
  COUNT(CASE data WHEN 2 THEN 1 ELSE NULL END) as Col2,
  COUNT(CASE data WHEN 3 THEN 1 ELSE NULL END) as Col3,
  COUNT(CASE data WHEN 4 THEN 1 ELSE NULL END) as Col4
FROM yourTable