Question

I have a results table which lists a set of values, each linking to another table containing the date that result was made.

I have working SQL to get all the dates (using CASE’s) however I can only retrieve a single range of results.

    Select 
    count(CASE
    WHEN  results.test_id IN ( SELECT id 
    FROM  `test` 
    WHERE  `posted` 
    BETWEEN  '2011-07-01 00:00:00'
    AND  '2011-07-01 23:59:59') 
    THEN results.test_id
    ELSE NULL
        END) AS "1st July"          
    from `results`
    WHERE results.window_id = 2 and results.mark > 90;

I also have another SQL query which gets all the ranges but can only work for one date at a time.

SELECT
CASE
    when mark > 90 then '>90%'
    when mark > 80 then '>80%'
    when mark > 70 then '>70%'
END as mark_results,
COUNT(*) AS count

FROM (SELECT mark from results where window_id =2) as derived
GROUP BY mark_results
ORDER BY mark_results;

What I’d like is to have everything in one unified query, displaying the relevant totals for each range of results. such as below:

Result Range | 1st July | 2nd July | 3rd July | 4th July
>90%         |    0     |    0     |    0     |    1
>80%         |    1     |    2     |    1     |    1
>70%         |    4     |    5     |    5     |    4

So that the totals for each range are displayed under their date.

I assume it’s possible.

Answer 1

The following statement joins results and tests in the FROM clause. It then aggregates the query by the mark range, with the counts per day:

Select (CASE when mark > 90 then '>90%'
             when mark > 80 then '>80%'
             when mark > 70 then '>70%'
       END) as mark_results,
     sum(case when posted BETWEEN  '2011-07-01 00:00:00' AND  '2011-07-01 23:59:59' then 1 else 0 end) as July01,
     sum(case when posted BETWEEN  '2011-07-02 00:00:00' AND  '2011-07-02 23:59:59' then 1 else 0 end) as July02,
     . . . 
from `results` r join
     test t
     on r.test_id = t.test_id
WHERE r.window_id = 2 and results.mark > 90
group by (CASE when mark > 90 then '>90%'
               when mark > 80 then '>80%'
               when mark > 70 then '>70%'
          END)
order by 1

Just add whatever days you want to the SELECT clause.

I should add . . . if you want all the dates, you need to put them on separate rows:

Select date(posted) as PostedDate,
      (CASE when mark > 90 then '>90%'
             when mark > 80 then '>80%'
             when mark > 70 then '>70%'
       END) as mark_results,
     count(*) as cnt
     . . . 
from `results` r join
     test t
     on r.test_id = t.test_id
WHERE r.window_id = 2 and results.mark > 90
group by date(posted),
         (CASE when mark > 90 then '>90%'
               when mark > 80 then '>80%'
               when mark > 70 then '>70%'
          END)
order by 1, 2

In fact, you might consider having a separate row for each date, with the ranges pivoted as columns.