SQL - Find Highest Single Day of Sales From Date Range - mysql

Question

I am using MySQL..
I have a simple sales table as follow:
o----o----------o-----------o
| id | store_id | logDate |
o----o----------o-----------o
| 1 | 1 | 2015-1-13 |
| 2 | 1 | 2015-1-14 |
| 3 | 2 | 2015-1-11 |
| 4 | 2 | 2015-1-18 |
o----o----------o-----------o
And sale product table
o----o----------o---------o------------o
| id | sale_id | qty | price |
o----o----------o---------o------------o
| 1 | 1 | 1 | 10 |
| 2 | 2 | 1 | 10 |
| 3 | 2 | 1 | 10 |
| 4 | 3 | 1 | 10 |
| 5 | 3 | 1 | 10 |
| 6 | 3 | 1 | 10 |
| 7 | 4 | 1 | 10 |
| 8 | 4 | 1 | 10 |
o----o----------o---------o------------o
Expected Result
o-- --------o----------------o---------------------o
| store_id | SUM(price*qty) | Highest Date On |
o-----------o----------------o---------------------o
| 1 | 20 | 2015-1-14 |
| 2 | 30 | 2015-1-11 |
O-----------o----------------o---------------------o
How to achieve my expected result?
I have tried as follow but it didn't work as expected:
SELECT store_id, MAX(total), highestSingleDateOn
FROM (
SELECT SUM(price * qty) AS total,
DATE(s.logDate) AS highestSingleDateOn, s.store_id AS store_id
FROM sale_product sp JOIN sales s ON s.id = sp.sales_id
GROUP BY DATE(s.logDate), s.store_id
ORDER BY DATE(s.logDate) ASC
) AS result_for_highest_single_day
GROUP BY highestSingleDateOn, store_id

Answer 1

SELECT store_id, MAX(total), highestSingleDateOn
FROM (
SELECT SUM(price * qty) AS total,
DATE(s.logDate) AS highestSingleDateOn, s.store_id AS store_id
FROM sale_product sp JOIN sales s ON s.id = sp.sales_id
GROUP BY DATE(s.logDate), s.store_id
ORDER BY total DESC
) AS result_for_highest_single_day
GROUP BY store_id
I just have modified the script ORDER BY DATE(s.logDate) ASC >> ORDER BY total DESC
and GROUP BY highestSingleDateOn, store_id >> GROUP BY store_id.
*Above sql script,it uses the unstable features about group by of MYSQL.
*Then according to Mysql standard,I write a other version sql script.
select table1.*
from
( SELECT SUM(price * qty) AS total,
DATE(s.logDate) AS highestSingleDateOn, s.store_id AS store_id
FROM sale_product sp JOIN sales s ON s.id = sp.sale_id
GROUP BY DATE(s.logDate), s.store_id) as table1
,
(select tmp.store_id,MAX(tmp.total) as max_total from
(SELECT SUM(price * qty) AS total,
DATE(s.logDate) AS highestSingleDateOn, s.store_id AS store_id
FROM sale_product sp JOIN sales s ON s.id = sp.sale_id
GROUP BY DATE(s.logDate), s.store_id ) as tmp group by tmp.store_id) as table2
where table1.store_id = table2.store_id and table1.total=table2.max_total

Answer 2

One way to do this in MySQL is with multiple an aggregations and then a join. Perhaps an easier way is to use variables:
SELECT sd.*
FROM (SELECT sd.*,
(#rn := if(#s = store_id, #rn + 1,
if(#s := store_id, 1, 1)
)
) as rn
FROM (SELECT DATE(s.logDate) AS date, s.store_id, SUM(price * qty) AS total
FROM sale_product sp JOIN sales s ON s.id = sp.sales_id
GROUP BY DATE(s.logDate), s.store_id
ORDER BY s.store_id, total desc
) sd cross join
(SELECT #rn := 0, #s := -1) params
) sd
WHERE rn = 1;