Question

(Please refer to SQLFiddle for a working example of this post)

I have a table with stock information, as follows:

sp100_id  _date         bullishness  agreement
----------------------------------------------
1         2011-03-16    1.01          0.33
1         2011-03-17    0.85          1.28
1         2011-03-18    0.89          1.25
1         2011-03-21    1.46          1.21
1         2011-03-22    0.39          2.53
2         2011-03-16    3.07          1.27
2         2011-03-17    2.09          0.80
2         2011-03-18    0.91          0.12
2         2011-03-21    1.50          0.00
2         2011-03-22    2.62          1.10
3         2011-03-16    0.73          1.13
3         2011-03-17    1.13          1.21
3         2011-03-18    1.12          0.45
3         2011-03-21    1.00          1.01
3         2011-03-22    1.00          0.53
4         2011-03-16    0.40          1.10
4         2011-03-17    2.40          0.03
4         2011-03-18    3.16          0.10
4         2011-03-21    0.86          0.50
4         2011-03-22    1.00          0.10

I need to order the companies (sp100_id) by their averge bullishness over time into a top-3:

SELECT 
  sp100_id, 
  AVG(bullishness) as bullishness, 
  AVG(agreement) AS agreement 
FROM stocks 
WHERE _date BETWEEN '2011-03-16' AND '2011-03-22' 
GROUP BY sp100_id LIMIT 3

This works fine, as the result is

SP100_ID    BULLISHNESS AGREEMENT
2           2.038           0.658
4           1.564           0.366
3           0.996           0.866

Now that I have the top-3, I need the top-3 to be re-ordered by AGREEMENT, ascending:

SP100_ID    BULLISHNESS AGREEMENT
4           1.564           0.366
2           2.038           0.658
3           0.996           0.866

Is this possible to do with one query? I tried the following but it didn’t work. It still only orders by bullishness

SELECT 
  sp100_id, 
  AVG(bullishness) as bullishness, 
  AVG(agreement) AS agreement 
FROM stocks 
WHERE _date BETWEEN '2011-03-16' AND '2011-03-22' 
GROUP BY sp100_id 
ORDER BY bullishness DESC, agreement ASC LIMIT 3

So to be clear: (1) I need to find the top-3 companies with highest average bullsihness (2) this top-3 then needs to be ordered from lowest to highest agreement. Preferably with one query. Do you know how?

Answer 1

It’s called structured query language because you can build structures in which queries (aka virtual tables) are nested inside other queries.

Take your first query, which is correct except it needs its own ORDER BY clause, and nest it in another, like so.

SELECT * 
  FROM (
           SELECT sp100_id,  
                  AVG(bullishness) as bullishness, 
                  AVG(agreement) AS agreement 
             FROM stocks 
            WHERE _date BETWEEN '2011-03-16' AND '2011-03-22' 
         GROUP BY sp100_id
         ORDER BY bullishness DESC
            LIMIT 3
  ) subquery
  ORDER BY agreement ASC

Go fiddle: http://sqlfiddle.com/#!2/c9ff0/7/0