Should/Must I use PDO::PARAM_NULL when binding a value that is null?

When preparing an SQL query using PDO, should/must I do

$query->bindValue('column', $value, is_null($value) ? PDO::PARAM_NULL : PDO::PARAM_STR);

Or I can just use PDO::PARAM_INT or PDO::PARAM_STR directly, because PDO figures that one out on its own? (as it really, really should in my opinion)

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And as a curiosity follow-up question, if I don’t have to use PDO::PARAM_NULL, what is it actually for?

Answer

No, you do not need to use PDO::PARAM_NULL. If you bind NULL with any type, then PDO will use NULL internally. The value will not be converted to a string, number or any other type. NULL will remain NULL.

When you set the type to PDO::PARAM_NULL it is equivalent to setting the value to NULL. One might argue that PDO::PARAM_NULL is useless as you can achieve the same results when binding NULL with any other type.

The following statements will both bind literal NULL value.

$str = 'someString';
$stmt->bindParam(1, $str, PDO::PARAM_NULL); 

$str = null;
$stmt->bindParam(1, $str, PDO::PARAM_STR);

$stmt->bindValue(1, null);