PDO statement select where date less than error - php

Question

I've spent 2 days trying to fix this - my date comparisons in MySQL aren't working when
trying to bind values with the <= less than or equals operator.
I've narrowed it down to the second date field (from a much more complicated script that changes the prepared statement joins/groups/fields/conditions depending on the request..hence why I am referring to table.column and selecting from only one table below - it works either way) but I can't make sense of it. The exact code used to work on php 5.x but I have just upgraded to php7.2.27.
Take the below SQL statement:
$sth = $this->prepare("SELECT
transaction.transactionid,
transaction.accountid,
transaction.userid,
transaction.billdate,
transaction.amount,
transaction.description,
transaction.confirmed
FROM transaction
WHERE
DATE(`billdate`) BETWEEN :startdate AND :enddate #date('2020-03-12')
ORDER BY billdate desc");
Trying to bind the following to it:
$terms = array(':startdate' => "2000-01-01",':enddate' => "2020-03-12");
foreach ($terms as $key => $value) {
if($value == (int)$value)
$sth->bindValue("$key", $value, PDO::PARAM_INT);
else
$sth->bindValue("$key", $value);
}
var_dump($sth);
var_dump($terms);
$sth->execute();
$this->rowCount = $sth->rowCount();
var_dump( $sth->fetchAll(PDO::FETCH_ASSOC));
This returns an empty array.
The table contains a handful of test rows. The below returns correctly:
...
DATE(`billdate`) BETWEEN :startdate AND '2020-03-12'
ORDER BY billdate desc
Wrapping the dates in date('date') seems to make no difference.
I've also tried this...
DATE(`billdate`) >= :startdate AND
DATE(`billdate`) <= '2020-03-12'
ORDER BY billdate desc
");
(Of course, changing the bound terms so that they mirror whatever I am using)
I need to be able to bind both variables.
Grateful for any pointers as I would love to avoid wasting another day debugging this!
Thanks

Answer 1

Just CAST to DATE:
WHERE billdate
BETWEEN CAST(:startdate AS DATE) AND CAST(:enddate AS DATE)"
And bind as PDO::PARAM_STR:
$sth->bindValue("startdate", "2000-01-01", PDO::PARAM_STR);
$sth->bindValue("enddate", "2020-03-12", PDO::PARAM_STR);