PHP PDO Declaración preparada vincular valor NULL

Esta es su consulta:

SELECT c.*, COUNT(d.servername) as servercount, d.controller
FROM customers C JOIN
     customerdata d
     ON c.id = d.customer
WHERE isVdi = :isVdi AND d.controller = :controller
GROUP BY d.customer
ORDER BY c.name ASC, c.environment ASC;

Desafortunadamente, cualquier cosa = NULL nunca va a volver verdad. Aún más lamentablemente, MySQL no es compatible con el estándar ANSI NULL -el comparador seguro is not distinct from . Pero felizmente tiene una alternativa. Puedes probar esto:

SELECT c.*, COUNT(d.servername) as servercount, d.controller
FROM customers C JOIN
     customerdata d
     ON c.id = d.customer
WHERE isVdi = :isVdi AND
      d.controller <=> :controller
GROUP BY d.customer
ORDER BY c.name ASC, c.environment ASC;