Re^3: SQL ERROR

Oh, yes and he is not using an RDMS either: just plain CSV-files!

How on earth do you know this?!? I've been following the thread and I haven't seen this tidbit. If so, I would assume the OP is using DBD::CSV, then. That's ... interesting. I wouldn't argue for it ... in fact, if there's any sort of reasonable work needing to be done in a reasonable time, porting to, at least, DBD::SQLite would be in order. Something that's written in optimized C as the engine for computationally-intensive bits is a must when doing any sort of serious work. This is why we don't use HTTP::Daemon when Apache/mod_perl is available.

Did you notice that he uses the LIKE-operator but does not include wildcards?

All that tells me is that the OP (and you) don't understand how DATEs work, especially in SQL. It is very expensive to convert a DATE to a CHAR, then perform a regex against it. Contrast that to using date arithmetic within the RDBMS, which is often optimized to use numeric vs. string comparisions.

The true solution is to fix the data source so that it's optimized to answer the question. Most RDBMSes will allow for a date to be "year-less", for just this type of query. Look it up.

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Comment on Re^3: SQL ERROR

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Re^4: SQL ERROR by CountZero (Bishop) on Nov 15, 2004 at 20:18 UTC
The error-string is a dead give-away: DBD::CSV::st execute failed: I'm quite sure DBD::CSV does not know how to use "year-less" dates. Indeed his SQL is strange (as you already pointed out), but you should not infer from the OP's knowledge of SQL, what my level of knowledge of SQL is. CountZero "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law	[reply]