PDO: Different results with SQLite BETWEEN - php

Question

I have a SQLite table with dates in unix timestamp format, which I query via PHP PDO. I'd like to mark the rows according to a date range, in my case whether the date falls in the winter semester or the summer semester of the year.
The start and end dates are arbitrary, but in my case I picked
start as March 1st (0301) and end as September 14th (0914), so I could easily check with BETWEEN.
When I run this query in PHP, like so, it returns an incorrect result ("WS" for all rows):
$statement = $db->prepare('SELECT CASE WHEN
(CAST(strftime("%m%d", class_date, "unixepoch") AS DECIMAL)
BETWEEN :start AND :end)
THEN "SS"
ELSE "WS" END
AS semester FROM dates');
$statement->execute(array(
':start' => 301,
':end' => 915
));
But when I embed the start and end dates as numbers, instead of binding them, it works correctly (some rows "WS", some "SS"):
$statement = $db->prepare('SELECT CASE WHEN
(CAST(strftime("%m%d", class_date, "unixepoch") AS DECIMAL)
BETWEEN 301 AND 915)
THEN "SS"
ELSE "WS" END
AS semester FROM dates');
$statement->execute();
What is happening here and how can I fix it? Any help is appreciated.

Answer 1

Documentation of PDOStatement::execute says that it accepts
An array of values with as many elements as there are bound parameters in the SQL statement being executed. All values are treated as PDO::PARAM_STR.
This means that even if you put in 301 it will be treated as "301".
Instead you should use PDOStatement::bindValue. Like this:
$statement->bindValue(':start', 301, PDO::PARAM_INT);
$statement->bindValue(':end', 915, PDO::PARAM_INT);
$statement->execute();