Set where conditions with desired DATE

Hello, need to create a table view that contains only records with the expired date (older than today) stored in the column named 'polTerm'.
The problem is that data is stored as string like 23.05.2019 ( dd.mm.yyyy); meaning it should be converted somehow.
So - the question is - how can I write the WHERE conditions in DB ReadData function to have this accomplished?
​
I have working code that hightlights the date in the table; now i want to show only those rows that contains expired date:

$polterm = $this->get('submissions_list.row.Submission.polTerm');  // stored as DD.MM.YYYY
$endDate = new DateTime($polterm); 
$curdate = new DateTime(date('d.m.Y'));

if($curdate > $endDate){
echo '<div style="color: red;">'.$this->get('submissions_list.row.Submission.polTerm').'</div>';
}else{
echo $this->get('submissions_list.row.Submission.polTerm');
}

Thank you in advance-
Elita

Try

date > DATEADD(day, 10, GetDate())

thanks, healyhatman,
khm. So "Where conditions" would be what? in the ReadData function?
Ifa I had date stored correctly, I would be able to have this code or smth like this, I believe
​

Submission.polTerm/<=: {date:Y-m-d} 

​
hovewer i have date stored as string in the format d.m.Y
​
So, how i can get this working?
​
Elita

I think I figured it out:

(STR_TO_DATE(polTerm,'%d.%m.%Y'))/<=:{date:Y-m-d}

However something seems "messing arround" - I cannot get that column to be ordered properly - it creates the order from days - 31.03.2019, 30.01.2019, 28.03.2019.... etc.
How can I fix this?

Put the column you want ordered by in the ordered by setting