Re: [GENERAL] count case when - PG 9.2

On 2017-03-09 05:27, Patrick B wrote:
> Hi guys. How can I count using 'CASE WHEN'?
>
> Example:
>
>>> SELECT
>>
>>> CASE
>>
>>> WHEN AND c.regdate > EXTRACT(epoch FROM (now() - INTERVAL
>>> '14 day'))
>>
>>> THEN 'trial'
>>
>>> WHEN last_pay > EXTRACT(epoch FROM (now() - INTERVAL '37
>>> day'))
>>
>>> THEN 'paying'
>>
>>> END as account_status,
>>
>>> c.id [1]
>>
>>> FROM public.clients c
>>
>>> WHERE (
>>
>>> (last_pay > EXTRACT('epoch' FROM now() - '12
>>> Months'::INTERVAL))
>>
>>> )
>>
>>> ORDER BY 1
>  I wanna know how many of 'trial' and 'paying' customers the query
> returns. can you guys please advice how to do it?
>
> Thanks
> Patrick
>

comparisons like "A>B" return a boolean. Booleans can be cast to
integers, and integers can be summed.

SUM((A>B)::int)

But depending on the situation, indexes etc it could be faster to run e
separate count query, you'll have to test that.