Query does not work as expected with bindParam but it does with raw input?

I have a query that should show all content from a specific date, like "show me all articles from 01-01-2020 to now".

The date is in unix. And I'm using PHP 7.2.

If I use bindParam instead of the real number, it shows content from within that date and older as well.

If I just type the number (the unix date), it shows the content ok, meaning that the content is all within the date range.

HERE'S MY QUERY:

  $y = $conectarDB->prepare("
      SELECT DISTINCT SQL_CACHE
      contenidos.contenidoID AS contID, 
      titulo, 
      fecha, 
      tipoContenidoID
      WHERE fecha > ?
      ORDER BY contenidoID DESC
  ");
  $y->bindParam(1, $fecha);
  $y->execute();
  $resultado = $y->fetchAll(PDO::FETCH_ASSOC);

Tying to sort it, I forced the date ($fecha variable) to be an integer, just in case the problem was that it was being interpreted as a string:

$fecha = (int)$fecha;

MySQL nor PHP show any errors, and the query gets excecuted, but showing older results as well, not following the range.

Solution

Just in case it helps someone in the future...

The problem was that the database field was a char type, instead of an integer.

So even with explicit declaration in PHP, MySQL kept considering it's contents as a string.

It was being read as:

  $y = $conectarDB->prepare("
      SELECT DISTINCT SQL_CACHE
      contenidos.contenidoID AS contID, 
      titulo, 
      fecha, 
      tipoContenidoID
      WHERE fecha > '1577847600'
      ORDER BY contenidoID DESC
  ");

Instead of:

  $y = $conectarDB->prepare("
      SELECT DISTINCT SQL_CACHE
      contenidos.contenidoID AS contID, 
      titulo, 
      fecha, 
      tipoContenidoID
      WHERE fecha > 1577847600
      ORDER BY contenidoID DESC
  ");

So, instead of just using:

  $y->bindParam(1, $fecha);

I've changed it to:

  $y->bindParam(1, $fecha, PDO::PARAM_INT);

To make MySQL understand that it is indeed an integer.