Re: [GENERAL] aggregate question

Hello out there,

many thanks for everybody helping with extracting month information
and so on from date columns.

Realizing that apparently a package with simple statistical
functions/aggregates like standard deviation doesn't exist, I have to
write one on my own. But, as stated earlier, I have problems
understanding the docs (i.e., the manual section "Extending SQL:
Aggregates"). This chapter is a little bit laconic (and others are,
too), and at least for the newcomers it is sometimes difficult to
guess the overall definition principle out of the three examples using
three unexplained for two explained keywords or functions.

I have the suspection that I will spend some hours in front of the
screen before I get a useful do-it-yourself-solution -- if anybody
knows something about more fool-proof documentation texts, or could
send me her or his own aggregate-defining-statements, I would be very
happy ;-)

Thanks in advance,
Ulf

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