从特定用户ID获取流

I am creating an application that fetches photos that users upload across my service and display it in a worldwide newsfeed.

I am having trouble creating the PHP MYSQL Code for a specific user with a specific user ID though, rather than everyone.

My database has the following in the photos table: IdPhoto, IdUser, title.

Here is how I am grabbing the worldwide feed (This works):

//stream API
//
// there are 2 ways to use the function:
// 1) don't pass any parameters - then the function will fetch all photos from the database
// 2) pass a photo id as a parameter - then the function will fetch the data of the requested photo
//
// Q: what "$IdPhoto=0" means? A: It's the PHP way to say "first param of the function is $IdPhoto, 
// if there's no param sent to the function - initialize $IdPhoto with a default value of 0"

function stream($IdPhoto=0) {

if ($IdPhoto==0) {

    // load the last 50 photos from the "photos" table, also join the "login" so that you can fetch the 
    // usernames of the photos' authors
    $result = query("SELECT IdPhoto, title, l.IdUser, username FROM photos p JOIN login l ON (l.IdUser = p.IdUser) ORDER BY IdPhoto DESC LIMIT 50");

} else {
    //do the same as above, but just for the photo with the given id
    $result = query("SELECT IdPhoto, title, l.IdUser, username FROM photos p JOIN login l ON (l.IdUser = p.IdUser) WHERE p.IdPhoto='%d' LIMIT 1", $IdPhoto);
}

if (!$result['error']) {
    // if no error occured, print out the JSON data of the 
    // fetched photo data
    print json_encode($result);
} else {
    //there was an error, print out to the iPhone app
    errorJson('Photo stream is broken');
}
}

I would like to do a similar deal. But for a specific user with a specific ID. Any suggestions on the MYSQL code / PHP code required for this?

I've tried the following for my profile function which didn't seem to work:

SELECT IdPhoto, IdUser,title, username FROM photos WHERE IdUser=$IdUser;

I am also calling the functions in my index.php file using cases:

case "stream":
    stream((int)$_POST['IdPhoto']);
    break;

Any idea what that would need to be for my profile function too?

The query should be:

SELECT IdPhoto, IdUser, title FROM photos WHERE IdUser = $IdUser;

Be sure to use single quotes when you are declaring variables; i.e. IdUser='$IdUser';.