for datetime intervals, don't return lowest value (min()) but avg()
authorgregor herrmann <gregor@toastfreeware.priv.at>
Thu, 30 Aug 2018 16:45:39 +0000 (18:45 +0200)
committergregor herrmann <gregor@toastfreeware.priv.at>
Thu, 30 Aug 2018 16:45:39 +0000 (18:45 +0200)
commitc078b6b5f231a2e7da614bcc6efcd0bb03c2fbeb
tree508bf0bfd39a5036096b5ad77a6314e034683a81
parent92df2c141c53707f26b0f1ac666940fb0ebc2f10
for datetime intervals, don't return lowest value (min()) but avg()

needs a conversion to/from unix timestamp

cf. https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html
and https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html
web/seepark_web.py