mysql insert max min value grouped by date - mysql

Question

This is my table schema:
mysql> describe stocks;
+-----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| symbol | varchar(32) | NO | | NULL | |
| date | datetime | NO | | NULL | |
| value | float(10,3) | NO | | NULL | |
| contracts | int(8) | NO | | NULL | |
| open | float(10,3) | NO | | NULL | |
| close | float(10,3) | NO | | NULL | |
| high | float(10,3) | NO | | NULL | |
| low | float(10,3) | NO | | NULL | |
+-----------+-------------+------+-----+---------+----------------+
9 rows in set (0.00 sec)
I added two new columns named high and low so they are empty now.
My goal is fill up these columns with the relative max(value),min(value) based on each daytime!
My first insight is this query:
select distinct DATE(date),max(value) as max,min(value) as min from stocks GROUP BY DATE(date);
...
| 2017-02-20 | 19130.000 | 18875.000 |
| 2017-02-21 | 19170.000 | 18780.000 |
| 2017-02-22 | 19125.000 | 18745.000 |
| 2017-02-23 | 18980.000 | 18765.000 |
| 2017-02-24 | 18840.000 | 18505.000 |
+------------+-----------+-----------+
that achieve the first step, now I should join these results with each rows:
| 900363 | FIB7C | 2017-02-20 17:49:44 | 18930.000 | 1 | 0.000 | 0.000 | 0.000 | 0.000 |
and insert the correct value based on DATE(date) but I still not catch to do with INSERT INTO.
Thanks for helps regards.

Answer 1

You can do this with a join in the update along with an aggregation to calculate the values:
update stocks s join
(select date(date) as d, max(value) as dhigh, min(value) as dlow
from stocks s
group by date(date)
) sd
on date(s.date) = sd.d
set s.high = sd.dhigh,
s.low = sd.dlow;