Query Bindings Problem

Hello!!

I have the next sentence, using pdo:

I have a problems where in the array parameters appear a variable type string:


$var1 = 1;
$var2 = 2;
$var3 = 'A';

$sentence = "SELECT column1, column2, column3 FROM table WHERE column1 = ? AND column2 = ? and column3 = ?";
$query = $this->db->query($sentence, array(intval($var1), intval($var2), strval($var3)));

And I get the next response:

A Database Error Occurred
Unsupported feature of the database platform you are using.


Where is the error??