>>> (2) What about cycles? How does one deal with them? >> With cycles, you probably want to use UNION instead of UNION ALL to >> stop at duplicate records.
>Hmmm... not quite sure how this would play out in practice... how would the >recursion known when to stop? >Say, given a circular hierarchy such as A-> B -> A.... when does the >recursion stop? UNION ALL means union all rows, even duplicates. UNION means union all DISTINCT rows. So it is not so much a matter of stopping as of not adding (hence recursing) from row A once it has already been seen. Read the docs. It explains how recursive CTEs are computed and how UNION ALL vs UNION work in CTEs. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
