PHP日期dd-mm-yyyy

I would like to fill a date in as dd-mm-yyyy but I would like to save the date as Y-m-d in my database. What I have is this:

Form:

$factuurDatum = new Zend_Form_Element_Text('datum');

Controller:

$data = $addInkoopfactuur->getValues();    
$data['datum'] = date("Y-m-d", strtotime($data['datum']));

But it doesn't work. I still get an error: '08-01-2014' and does not fit the date format 'yyyy-MM-dd'. How can I resolve this problem?

Got the problem myself! the addvalidator('Date', true) should be deleted in my form! Because the validator will set my date as yyyy-mm-dd. My question was not answered clear enough, sorry!

Use this DateTime class

<?php
    $pubDt='07-01-2014';
    $date = DateTime::createFromFormat('d-m-Y', $pubDt);
    echo $newPubdate = $date->format('Y-m-d');

DEMO : https://eval.in/86800
Did you want it?

$data['datum'] = "15-10-2013";
$data['datum'] = date("Y-m-d", strtotime($data['datum']));

echo $data['datum'] ;

OUTPUT:

2013-10-15