on the update page, you would use the recordset binding for the initial value:
<?php echo $row_recordsetName['dateColumn']); ?>
you would use the same date and str_to_time function to convert it to the format you like:
<?php echo(date("d-m-Y", strtotime($row_recordsetName['dateColumn']))); ?>
and use the same code to at line 1 of the update page to convert it back.