在同一查询中具有不同条件的Postgres计数

Question

I'm working on a report which has this following schema: http://sqlfiddle.com/#!15/fd104/2

The current query is working fine which looks like this:

Basically it is a 3 table inner join. I did not make this query but the developer who left it and I want to modify the query. As you can see, TotalApplication just counts the total application based on the a.agent_id . And you can see the totalapplication column in the result. What I want is to remove that and change the totalapplication to a new two column. I want to add a completedsurvey and partitalsurvey column. So basically this part will become

SELECT a.agent_id as agent_id, COUNT(a.id) as CompletedSurvey
FROM forms a WHERE  a.created_at >= '2015-08-01' AND 
a.created_at <= '2015-08-31' AND disposition = 'Completed Survey'
GROUP BY a.agent_id

I just added AND disposition = 'Completed Survey' But I need another column for partialsurvey which has the same query with completedsurvey being the only difference is

AND disposition = 'Partial Survey'

and

COUNT(a.id) as PartialSurvey

But I dunno where to put that query or how will be the query look like.So the final output has these columns

agent_id, name, completedsurvey, partialsurvey, loginhours, applicationperhour, rph

Once it is ok then applicationperhour and rph I can fix it myself

Answer 1

If I understand you correctly, you are looking for a filtered (conditional) aggregate:

SELECT a.agent_id as agent_id, 
       COUNT(a.id) filter (where disposition = 'Completed Survey') as CompletedSurvey, 
       count(a.id) filter (where disposition = 'Partial Survey') as partial_survey
FROM forms a 
WHERE a.created_at >= '2015-08-01' 
  AND a.created_at <= '2015-08-31' 
GROUP BY a.agent_id;

The above assumes the current version of Postgres (which is 9.4 at the time of writing). For older versions (< 9.4) you need to use a case statement as the filter condition is not supported there:

SELECT a.agent_id as agent_id, 
       COUNT(case when disposition = 'Completed Survey' then a.id end) as CompletedSurvey, 
       COUNT(case when disposition = 'Partial Survey' then a.id end) as partial_survey
FROM forms a 
WHERE a.created_at >= '2015-08-01' 
  AND a.created_at <= '2015-08-31' 
GROUP BY a.agent_id;