Demeow sqlite patch

Tagging for perusal later.

The merge fix is already in #332002: MergeQuery should refuse to execute if there are no key fields. But that issue is on the verge of derailing.

Ok, tested the affected part. Good to go.

And again... :)

Could someone explain this hunk?

-    $this->assertErrorMessage('PDOException', 'system_test.module', 'system_test_trigger_pdo_exception()', 'Base table or view not found');
+    $this->assertErrorMessage('PDOException', 'system_test.module', 'system_test_trigger_pdo_exception()', 'SQLSTATE');

Looks like that's meant to be a constant? or..?

See this : http://fr2.php.net/manual/en/pdo.errorcode.php

Briefly, an SQLSTATE consists of a two-character class value followed by a three-character subclass value.

and also : http://developer.mimer.com/documentation/html_92/Mimer_SQL_Engine_DocSet...

Ok cool. But it's wrapped in single quotes. Bug?

Added a code comment about that.

While this is a blocker for SQLite, it's not a blocker for UNSTABLE-3. Adjusting title accordingly.

To clarify, this patch changes three things:

1) It removes the required bit from the username field in the database settings, since some database systems (such as SQLite) do not require it.
2) It fixes an incorrect merge query in aggregator module. This doesn't fire errors in MySQL because MySQL's merge implementation that relies on the internal mysql collisions and not the keys.
3) It genericizes an error check in one of the tests so that it works across database systems.

What befuddled me above was I wasn't counting arguments so thought 'SQLSTATE' was the message displayed when the assertion was triggered, not the error message to check for. It's kinda crappy that we can't get any more fine-grained than "SQLSTATE" because that'll likely be triggered for almost any error. However, Damien and chx told me that even the specific error number varies from platform to platform, so this is the best we can do for now. :\

Tonight I'm working on UNSTABLE-3 but can commit this tomorrow.

Ok, committed!