不同，计数，按查询疯狂分组

Question

I am trying to return a count of tests taken per term. I can get the count to return, but I can't get it grouped by term.

I've tried everything and the closest I get is grouping by term but then my count only = 1, which isn't right.

Here is what I have now. It just returns a count, how do I group it by term_id?

SELECT COUNT(*) 
  FROM (SELECT DISTINCT ON(student_id, test_event_id, terf.term_id) student_id  
          FROM report.test_event_result_fact terf 
          JOIN report.growth_measurement_window gw on gw.term_id = terf.term_id 
          JOIN report.term t on t.term_id = terf.term_id 
          JOIN report.test tt on tt.test_id = terf.test_id 
         WHERE terf.partner_id = 98 
           AND growth_event_yn = 't' 
           AND gw.test_window_complete_yn = 't' 
           AND gw.growth_window_type = 'DISTRICT' 
           AND tt.test_type_description = 'SURVEY_WITH_GOALS') as TestEvents

Answer 1

Without knowing more about your setup, that's my best bet:

select term_id, count(*) AS count_per_term
  from (
    select Distinct on (student_id, test_event_id, terf.term_id)
            terf.term_id, student_id
      from report.test_event_result_fact terf
      join report.growth_measurement_window gw using (term_id)
      join report.term t using (term_id)
      join report.test tt using (term_id)
     where terf.partner_id = 98
        and growth_event_yn = 't'
        and gw.test_window_complete_yn = 't'
        and gw.growth_window_type = 'DISTRICT'
        and tt.test_type_description = 'SURVEY_WITH_GOALS') as TestEvents
  group by 1;