In this particular case you could say

	... GROUP BY 1 ORDER BY 1;

"ORDER BY n" as a reference to the n'th SELECT output column is in the
SQL92 spec.  (IIRC they removed it in SQL99, but we still support it,
and I think most other DBMSes do too.)  "GROUP BY n" is *not* in any
version of the spec but we allow it anyway.  I'm not sure how common
that notation is.

  

SELECT enddate, count(*) FROM (
    SELECT date_trunc('day', endtime) AS enddate FROM eg_event WHERE
endtime >= '2006-01-01'  and endtime < '2006-03-01') as foo
GROUP BY enddate
ORDER BY enddate


It brings up a question though: is there any way in Postgres to set a "quirks" or "standards" mode.  Or get Postgres to log the compliance level of each command and command element used, e,g.:

It is so easy to get lazy and start shrink-wrapping code to the database.  That's certainly why mysql SQL tends to be so non-portable....