Return a record set with no rows

I use pdo to pull queries down from MySQL which has worked fine by using

$rs->fetchAll(PDO::FETCH_ASSOC);

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The problem is when there is no rows to retrieve it returns an empty array (which I understand is right), however is there a way I can return the structure (the fields that would be returned) and if possible have the field values as null, so long as the fieldnames are available in the returned array

So, for example:-

SELECT * FROM `modules` WHERE `moduleID` =1;

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Which returns 1 row:-

Which returns the array:-

Array
(
    [moduleID] => 1
    [title] => Employees and Contractors
    [permissionPath] => NULL
    [order] => 100
    [colorHex] => 436D5D
)

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What I would like it is to use a query like:-

SELECT * FROM `modules` WHERE `moduleID` IS NULL

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Which returns 0 rows:-

And Id like the returned array to be:-

Array
(
    [moduleID] => NULL
    [title] => NULL
    [permissionPath] => NULL
    [order] => NULL
    [colorHex] => NULL
)

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Is this even possible