(no subject)

[nolly]

MySQL is kicking my tail.


Here's the query so far:
select d.scheduleDigest, c.userID, c.initDate, a.classroomID, b.startDate, b.stopDate, c.benchmarkName, a.benchmarkDigest, b.part, b.sessionNumber, c.fbDigest
from benchmarkClassrooms as a, benchmarks as c, benchmarkSessions as b LEFT JOIN schedule as d
ON b.benchmarkDigest = d.benchmarkDigest and b.sessionNumber = d.benchmarkSession and b.part = d.benchmarkPart
where a.benchmarkDigest = b.benchmarkDigest and a.benchmarkDigest = c.benchmarkDigest and a.clientID = 'darkmatter' and c.msgPrior >= to_days(b.startDate) - to_days(NOW()) and b.stopDate >= NOW();

(well, there's a bit more to the full query, but this'll do for now.)

The problem: It's, er, multiplexing on classroomID. (I'm sure there's a technical term for that, but I don't know/have forgotten it.) I need, basically, a left join between a and d, on benchmarkDigest and classroomID. (And yes, it has to be a left join; ultimately, a where schduleDigest IS NULL will be added, as I'm looking for tests that have not been scheduled.) I can't seem to make this work. Is it possible in a single query, using MySQL 4.whatever? (that is to say, the current released version, 4.0.23 or whatever it is)

Point me at any SQL or MySQL communities you're aware of, too.