MYSQL合并，计数和分隔ID相同但值不同的行实例

Question

目前，我有一个查询类似

，查询写成这样：

SELECT username, exerciseId, frustrated, bored 
FROM affecttutor.selfreportfrustration 
order by username;

我正在尝试使其看起来像这样

可能会做些什么？谢谢您的宝贵时间！

Answer 1

您可以尝试使用条件聚合

select 
   username,exerciseid,
   count(case when frustrated='Y' then 1 end) as frustrated,
   count(case when frustrated<>'Y' then 1 end) as notfrustrated,
   count(case when bored<>'N' then 1 end) as bored ,
   count(case when bored='N' then 1 end) as notbored
from affecttutor.selfreportfrustration
group by username,exerciseid