Table Name in JSON Encoded Array

I'm trying to write a script to accept data from an iPhone app onto a webpage. The data is a user signup. Once the user is signed up, I need to throw back in JSON a success message, the users ID and the table name like this:

I need to list the table name within a custom JSON encoded array like this:

{
"users": [
{ "success":"true" ,"userID":".$row['userID']."}
]
}

PHP:

This is what I have so far, but I'm really struggling to get the table name within the JSON array but outside of the variables;

            //Account created, generate success response
            $message = array(
                 'success'=>'true',
                'userID'=>''.$row['$userID'].''
                );
            echo json_encode($message);
        }

PHP:

It looks like this:

 

$message = array(
    'users' => array(
        'success'=>'true',
        'userID'=>''.$row['$userID'].''
    )
);
echo json_encode($message);

PHP:

This should do it.

 

Nope, I need it to be in the square brackets like this:

{
"users": [
{ "success":"true" ,"userID":".$row['userID']."}
]
}

Code (markup):

 

Managed to get it working with:

            //Account created, generate success response
            $message = array(
            "users" => array (array(
            'success'=>'true',
            'userID'=>''.$row['userID'].''
            )));
echo json_encode($message);

PHP: