CASE 语句中尚不支持 UDAF 'count' 的位置

Question

当我执行下面的查询时，我得到错误 "count" is not supported in case statements。想知道是否有解决此问题的方法。

    select 
    sum(case when a.key1 == 80 then count(distinct a.key2) else 0 end) as no_80_counts,
    from table1

Answer 1

不支持嵌套聚合函数。你想多了。

select count(distinct key2) as no_80_counts,
from table1
where key1 = 80

或

select count(distinct case when key1=80 then key2 end) as no_80_counts,
from table1

删除 where 子句和 group by key1 以获得所有 key1 的不同 key2 计数。