I can't find any information on these constants but the sparse bit the documentation gives.
What can they be used for, and do I to use them?
+1
A:
As far as I can tell, you cannot use them as an end-user. Those constants are used internally on a per-driver basis for handling of the events described. Browsing the source at http://svn.php.net/repository/php/php-src/branches/PHP_5_3/ext/ I did not find any end-user functionality.
Wrikken
2010-07-25 23:26:51
I had hoped for some way of injecting callbacks for those events. Thank you very much for your answer.
antennen
2010-07-26 07:45:42
Except for the `alloc`/`free` variants, you can create your hooks to events quite easily by extending the `PDO` and/or `PDOStatement` class.
Wrikken
2010-07-26 08:17:24