Mention MySQL sql_mode in the docs.

If it helps just one person avoid getting bitten by MySQL's default data-munging
retardedness, it'll have been worth it.

lib/Dancer/Plugin/Database.pm

@@ -379,7 +379,19 @@ documentation for these.
 
 The optional C<on_connect_do> setting is an array of queries which should be
 performed when a connection is established; if given, each query will be
-performed using C<< $dbh->do >>.
+performed using C<< $dbh->do >>.  (If using MySQL, you might want to use this to
+set C<SQL_MODE> to a suitable value to disable MySQL's built-in free data loss
+'features', for example:
+
+  on_connect_do: "SET SQL_MODE='TRADITIONAL'"
+
+(If you're not familiar with what I mean, I'm talking about the insane default
+behaviour of "hmm, this bit of data won't fit the column you're trying to put it
+in.. hmm, I know, I'll just munge it to fit, and throw a warning afterwards -
+it's not like you're relying on me to, y'know, store what you ask me to store".
+See L<http://effectivemysql.com/presentation/mysql-idiosyncrasies-that-bite/> for
+just one illustration.  In hindsight, I wish I'd made a sensible C<sql_mode> a
+default setting, but I don't want to change that now.)
 
 The optional C<log_queries> setting enables logging of queries generated by the
 helper functions C<quick_insert> et al in L<Dancer::Plugin::Database::Handle>.