>is possible to get week of the year "within year"?

>I see that built in functions only support ISO-8601 (or i do not know some parameter)

Actually, Karol, “week within year” is not the week, Karol. 1 January could be week 53 and 31 December could be week 1. If you want to consider 1 January always as part of week 1 (even if that day could be the only day of week 1), I’d suggest you try something like:

select (extract(yearday from cast('1.1.2014' as date))-extract(weekday from cast('1.1.2014' as date)))/7+1

from rdb$database

If you want the first seven days of a week to always be week 1 (and changing which day a week start with for each year), you could drop the second EXTRACT.

HTH,

Set