PDO: How to fetch TIMESTAMP values?

I recently began evaluating the feasibility of reworking our current database access framework, which utilizes the PHP-native drivers for our database (Interbase), to one which makes use of the PDO extension. Unfortunately, I quickly hit a roadblock. I have tried every permutation available in the PDO documentation, as far as I can see, in order to retrieve the value of a TIMESTAMP-type field from a given table, but so far I have been unsuccessful. Using the PHP-native functions for Interbase, I used to be able to accomplish this with the following code: <?php $sql = "SELECT TIMESTAMP_FIELD FROM MY_TABLE"; $result = ibase_query($dbh, $sql); $row = ibase_fetch_row($result, IBASE_UNIXTIME); $field = $row[0]; echo "$field"; ?> Here is one of the many [failed] methods I have attempted using a PDO: <?php $sql = "SELECT TIMESTAMP_FIELD FROM MY_TABLE"; $row = $dbh->query($sql); $field = $row['TIMESTAMP_FIELD']; echo "$field"; ?> In the first instance, a numeric (integer) value would be displayed on the screen. In the PDO example, nothing is displayed. I have also tried rewriting the PDO code above as a prepared statement, but i get the same result. Has anyone else bumped up against problems with TIMESTAMP fields when using the Interbase PDO driver or some other? Any suggestions would be appreciated. Thanks!