Michael Bayer wrote > On Dec 12, 2007, at 9:04 AM, King Simon-NFHD78 wrote: > > > > > Hi, > > > > I'm connecting to an ancient version of MySQL (3.23.58) > that (as far > > as > > I can tell) doesn't support basic "JOIN <table> ON > <condition>" syntax > > > > Ie. this gives a syntax error: > > > > SELECT * FROM productversions pv > > JOIN producttypes pt ON pv.producttype = pt.producttype > > > > Whereas this is fine: > > > > SELECT * FROM productversions pv > > JOIN producttypes pt > > WHERE pv.producttype = pt.producttype > > > > Can anyone think of anything I can do (perhaps by subclassing or > > monkeypatching MySQLDialect) to automatically convert > queries like the > > former into the latter? SQLAlchemy seems to be infitely flexible in > > dealing with syntax quirks of various databases, so I've got my > > fingers > > crossed... > > > > this is possible, we do it in the oracle module when the ansi=False > flag is set. if you look at the visit_join code in oracle.py, you > could probably lift that up and stick it right in mysql.py, have it > activated by a dialect flag, and it would work. > > however, if the database doesnt support JOIN..ON, that > indicates that > its impossible to do an OUTER JOIN. oracle used a special > operator > (+) to indicate the "outerness" of a join..does this old mysql have > anything for that ? otherwise it doesnt seem much worth it to > support JOIN at all when you could just select from two tables. >
I knew SA could do it! Thanks! This version of MySQL does support LEFT JOIN and RIGHT JOIN, so things like eager loads work correctly (as far as I can tell). Does that mean that in visit_join, I should defer to the normal implementation if join.isouter is True? This came up because I was using query.join to filter a query based on a child's attributes, and suddenly the query stopped working on MySQL. I was about to try and find all occurrences of query.join and change them to explicit filter conditions, but if I can make the visit_join method work, I would much prefer to do it that way. I'll let you know if it works - it may be worth adding as an optional behaviour to MySQLDialect (although if I'm the only one that's come across the problem, maybe no-one else is using a version of MySQL that's this old) Thanks, Simon --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
