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Re: Tree Structure and Db

by sharkey (Scribe)
on Jul 06, 2005 at 02:08 UTC ( #472660=note: print w/replies, xml ) Need Help??

in reply to Tree Structure and Db

This probably won't help you, but...

If you happen to be using Oracle or DB2, those databases have SQL extensions to do tree structured queries, based on a table like you describe.

The syntaxes are radically different, so your best bet is to look it up in your database documentation. For Oracle the keyword is "CONNECT BY", and for DB2 the keyword is "WITH".

Here's a nice overview:

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Re^2: Tree Structure and Db
by hartwig (Sexton) on Jul 07, 2005 at 11:21 UTC
    CONNECT BY is not working very well in oracle 9.2 - in oracle 8.X its OK. This is a bug in oracle 9.2 (also admited by oracle ;)) -
    What kind of DB are you using?
    Best regards
      I use MySQL 4.x

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[ambrus]: Corion: as for that, I talked with schmorp, and looked a bit more at Prima
[ambrus]: Corion: from the docs, it definitely looks like it would be possible to write an AnyEvent driver for it using Prima::File and Prima::Timer.
[ambrus]: (I haven't found an idle event.)
[ambrus]: However, I also looked at the internals, and found two interesting things:
[marto]: stupid xpath question, I have a xpath copied from the browser, is the * wildcard supposed to work for IDs? e.g. '//*[@id="*"]/ div/div/header/p/a '?
[ambrus]: The main loop for unixish systems is in https://metacpan. org/source/ KARASIK/Prima-1. 49/unix/apc_app.c. It is a hand-rolled select loop, but also always spins at least once every 0.2 seconds for some reason.
[ambrus]: marto: no, not that way. if you just want to test for an existing id attribute, then write *[@id] , or you can match a regexp to the value of that attribute like *[@id=~/something/ ]
[marto]: ambrus, thanks I ended up going with '//*[starts- with(@id, "thread_")]...

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