如何通过`count（*）`过滤intems而不用`having`？

Question

我有一些疑问：

select disconnect_reason as disconnectReason, disconnect_cause, count(*) as callsCount 
from calls group by disconnect_reason, disconnect_cause 

我如何才能获得callCount = 1的项目 如何在没有having的情况下获得它？

Answer 1

总是可以使用Having子句来过滤组，但如果你想要另一种方式，那么试试这样的事情

select * from 
(
select disconnect_reason as disconnectReason, disconnect_cause, count(*) as callsCount 
from calls group by disconnect_reason, disconnect_cause
) A
Where callsCount = 1

Answer 2

尝试使用 CTE 对于 MS SQL SERVER

with cte
as
(
select disconnect_reason as disconnectReason, disconnect_cause, count(*) as callsCount 
from calls group by disconnect_reason, disconnect_cause 
)
select * from cte where callsCount >0

Answer 3

select *
from
(
select disconnect_reason as disconnectReason, disconnect_cause, count(*) as callsCount 
from calls group by disconnect_reason, disconnect_cause
)base
where  callsCount = 1