Thanks for your input, Thufir, but I've tried to keep the example that 
illustrates the problem down to bare essentials. I'm afraid introducing 
additional objects (yaml, item, open-uri, pp) won't help - i.e. if my 
example doesn't work for me, there's no reason yours will.

An interesting additional clue to the problem is that using the mysql 
gem directly (with the same query above for which activerecord generated 
an exception) as shown below, DOES work:


require 'mysql'

db = Mysql.new('localhost', 'root', '', 'test')
rs = db.query('INSERT INTO `a` (`x`) VALUES(5)')


Is there some kind of incompatibility between activerecord gem v2.3.4 
and mysql gem v2.8.1 (or some other gem activerecord requires to 
properly use the mysql gem)?

Again, any clues would be greatly appreciated!
-- 
Posted via http://www.ruby-forum.com/.