SQL to find max of sum of data in one table, with extra columns - sql

Question

Apologies if this has been asked elsewhere. I have been looking on Stackoverflow all day and haven't found an answer yet. I am struggling to write the query to find the highest month's sales for each state from this example data.
The data looks like this:
| order_id | month | cust_id | state | prod_id | order_total |
+-----------+--------+----------+--------+----------+--------------+
| 67212 | June | 10001 | ca | 909 | 13 |
| 69090 | June | 10011 | fl | 44 | 76 |
... etc ...
My query
SELECT `month`, `state`, SUM(order_total) AS sales
FROM orders GROUP BY `month`, `state`
ORDER BY sales;
| month | state | sales |
+------------+--------+--------+
| September | wy | 435 |
| January | wy | 631 |
... etc ...
returns a few hundred rows: the sum of sales for each month for each state. I want it to only return the month with the highest sum of sales, but for each state. It might be a different month for different states.
This query
SELECT `state`, MAX(order_sum) as topmonth
FROM (SELECT `state`, SUM(order_total) order_sum FROM orders GROUP BY `month`,`state`)
GROUP BY `state`;
| state | topmonth |
+--------+-----------+
| ca | 119586 |
| ga | 30140 |
returns the correct number of rows with the correct data. BUT I would also like the query to give me the month column. Whatever I try with GROUP BY, I cannot find a way to limit the results to one record per state. I have tried PartitionBy without success, and have also tried unsuccessfully to do a join.
TL;DR: one query gives me the correct columns but too many rows; the other query gives me the correct number of rows (and the correct data) but insufficient columns.
Any suggestions to make this work would be most gratefully received.
I am using Apache Drill, which is apparently ANSI-SQL compliant. Hopefully that doesn't make much difference - I am assuming that the solution would be similar across all SQL engines.

Answer 1

This one should do the trick
SELECT t1.`month`, t1.`state`, t1.`sales`
FROM (
/* this one selects month, state and sales*/
SELECT `month`, `state`, SUM(order_total) AS sales
FROM orders
GROUP BY `month`, `state`
) AS t1
JOIN (
/* this one selects the best value for each state */
SELECT `state`, MAX(sales) AS best_month
FROM (
SELECT `month`, `state`, SUM(order_total) AS sales
FROM orders
GROUP BY `month`, `state`
)
GROUP BY `state`
) AS t2
ON t1.`state` = t2.`state` AND
t1.`sales` = t2.`best_month`
It's basically the combination of the two queries you wrote.

Answer 2

Try this:
SELECT `month`, `state`, SUM(order_total) FROM orders WHERE `month` IN
( SELECT TOP 1 t.month FROM ( SELECT `month` AS month, SUM(order_total) order_sum FROM orders GROUP BY `month`
ORDER BY order_sum DESC) t)
GROUP BY `month`, state ;