选择的ID数

Question

在下面的sql小提琴中，我如何更改视图以获得所需的输出？

http://sqlfiddle.com/#!6/a737a/1

查看

select
    sum(dollars) as totalDollars,
    sum(dollars)/count(id) as factor,
    count(id) as numberOfEvents, 
    id as eventID,
    event_date
from
    events
group by
    id,
    event_date

查询

select
*
from eventStats
where 
event_date between '1/1/2015' and '1/16/2015'

期望的输出

numberOfevents应该= 2（事件的实际数量，而不是每个事件的记录数，由查询中的where子句确定），以便在视图中正确地进行数学运算。

Answer 1

没有count条款，你可以distinct fk_id group by：

select count(distinct fk_id) as number_of_IDs
from [myTable]
where [someCondition]

Answer 2

在distinct函数中使用count关键字：

select
    count(distinct fk_id) as number_of_IDs
    ,id
from
    myTable
where
    someCondition
group by
    id