That was not a ready copy-paste solution, but rather a direction to move. Main idea was to have two queries - one for yesterday, one for today.
I.e. (again, just examples, not ready-to-use solutions):
SELECT mean("value") FROM "stal_soc" WHERE ("time" > now() - 1d AND "time" < now()) GROUP BY time(1m) fill(null)
and
SELECT mean("value") FROM "stal_soc" WHERE ("time" > now() - 2d AND "time" < now()-1d) GROUP BY time(1m) fill(null)
Also, if you can use flux instead of InfluxQL, that would be much easier to implement. There are several topics at this forum that cover details on this: one, two etc.