January 2008
Intermediate to advanced
384 pages
8h 1m
English
Content preview from Joe Celko's Thinking in Sets: Auxiliary, Temporal, and Virtual Tables in SQLBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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5.2. Permutations
Mike Whiting asked for code to generate all the possible permutations of a string. This was a popular problem in the British Computer Journal a few decades ago. They published several Algol programs with good discussions at that time. A good reference website is http://portal.acm.orglcitatioN.cfm?id=356692, but you can find others. But because they were written for a procedural programming language, many of the articles focus on the sequence of generation of permutations, rather than just getting the entire set.
5.2.1. Permutations via Recursion
Alex Kuznetsov replied with a recursive CTE solution that assumes an auxiliary Sequence table. Begin by setting the :input_str = ’ABCDE’ and running this query:
WITH RECURSIVE Subsets ...
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