Description:
------------
Description can also be found here:
http://stackoverflow.com/questions/11415314/pdo-invalid-parameter-number-parameters-in-comments/

The problem is simple: PDO throws an exception when using named or positional parameters in SQL comments. This is unexpected behaviour and costed me quite a while to figure out.

The thrown exceptions for named and positional parameters are, respectively:

Warning: PDOStatement::execute() [pdostatement.execute]: SQLSTATE[HY093]: Invalid parameter number:
Warning: PDOStatement::execute() [pdostatement.execute]: SQLSTATE[HY093]: Invalid parameter number: mixed named and positional parameters

Test script:
---------------
Try executing this query using PDO:

SELECT
    x
FROM
    y
WHERE
    -- CHECKING IF X = ? --
    x = :y
AND
    1 = 2

Or this one:

SELECT
    x
FROM
    y
WHERE
    -- CHECKING IF X = :Z --
    x = :y
AND
    1 = 2

Expected result:
----------------
This should execute the query with only :Z as bound parameter.

Actual result:
--------------
Exceptions because parameters in comments get parsed.