[firebird-support] SQL standard for sort fields and returned fields

[liviuslivius liviusliv...@poczta.onet.pl [firebird-support]]

Hi,
 
This is not specific to Firebird question but:
is something in SQL standard specification about sorted fields must be also 
returned?
I mean:
 
SELECT 
[FILM_DATE,]FILM_TITLE
FROM
FILMS
ORDER BY FILM_DATE, FILM_TITLE
 
is [FILM_DATE] required by SQL standard or it is optional or SQL standard tell 
nothing about this?
 
regards,
Karol Bieniaszewski