Gathering data from database

The following code has one of the most confusing lines I've ever wrote. I can imagine ten other way to write it but I do not know which else could be any better. So I'm here to ask you fellows how would you change this code. I feel like the context is self explaining itself here; if you need of any clarification write a comment below.

Notice:

Db() is very similar to PDO(), it just extends it adding few features I'm not using here.

Post::addExtra() add abstract datas elaborating database data. For example he created a $data[13] = $data['from db1'] .' with '. $data['from db2']. These because they are going to be passed to the template.

$db = new Db();
$s = new Session();

# Default statement and parameters
$stmt = 
"SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
    (
        SELECT COUNT(*)
            FROM Flags as f 
                JOIN Posts as p1
                ON p1.PostPID = f.FlagPID
            WHERE p1.PostPID = p.PostPID
    ) as PostFlags
    FROM Posts AS p
        JOIN Users AS u
        ON p.PostUID = u.UserUID
    ORDER BY PostTime DESC
    LIMIT 0, 30";
$par = array();

# We change the statement if the tab is selected
if ($tab = get('tab')) {
    switch ($tab) {
        case 'admin':
            $stmt = 
            "SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
            (
                SELECT COUNT(*)
                    FROM Flags as f 
                        JOIN Posts as p1
                        ON p1.PostPID = f.FlagPID
                    WHERE p1.PostPID = p.PostPID
            ) as PostFlags
                FROM Posts AS p
                    JOIN Users AS u
                    ON p.PostUID = u.UserUID
                WHERE p.PostUID = 1
                ORDER BY PostTime DESC
                LIMIT 0, 30";
            break;
        case 'trusted':
            if ($s->isLogged()) {
                $stmt = 
                "SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
                (
                    SELECT COUNT(*)
                        FROM Flags as f 
                            JOIN Posts as p1
                            ON p1.PostPID = f.FlagPID
                        WHERE p1.PostPID = p.PostPID
                ) as PostFlags
                    FROM Posts AS p
                        JOIN Users AS u
                        ON p.PostUID = u.UserUID
                    WHERE p.PostUID IN (
                        SELECT TrustedUID
                        FROM Trust
                        WHERE TrusterUID = :uid
                    )
                    ORDER BY PostTime DESC
                    LIMIT 0, 30";
                $par = array('uid' => $s->getUID());
            } else {
                $stmt = '';
            }
            break;
        case 'favorite':
            if ($s->isLogged()) {
                $stmt = 
                "SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
                (
                    SELECT COUNT(*)
                        FROM Flags as f 
                            JOIN Posts as p1
                            ON p1.PostPID = f.FlagPID
                        WHERE p1.PostPID = p.PostPID
                ) as PostFlags
                    FROM Posts AS p
                        JOIN Users AS u
                        ON p.PostUID = u.UserUID
                    WHERE p.PostPID IN (
                        SELECT FavoritePID
                        FROM Favorites
                        WHERE FavoriteUID = :uid
                    )
                    ORDER BY PostTime DESC
                    LIMIT 0, 30";
                $par = array('uid' => $s->getUID());
            } else {
                $stmt = '';
            }
            break;
        case 'top':
            $weekAgo = time() - week;
            $monthAgo = time() - month;
            $stmt = 
            "SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
            (
                SELECT COUNT(*)
                    FROM Flags as f 
                        JOIN Posts as p1
                        ON p1.PostPID = f.FlagPID
                    WHERE p1.PostPID = p.PostPID
            ) as PostFlags
                FROM Posts AS p
                    JOIN Users AS u
                    ON p.PostUID = u.UserUID
                WHERE p.PostTime > $monthAgo
                LIMIT 0, 3
            UNION
            SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
            (
                SELECT COUNT(*)
                    FROM Flags as f 
                        JOIN Posts as p1
                        ON p1.PostPID = f.FlagPID
                    WHERE p1.PostPID = p.PostPID
            ) as PostFlags
                FROM Posts AS p
                    JOIN Users AS u
                    ON p.PostUID = u.UserUID
                WHERE p.PostTime > $weekAgo
                ORDER BY PostFlags DESC
                LIMIT 0, 30";
            break;
        case 'recent':
        default:
            break;
    }
} 

# Loading posts
try {
    $sql = $db->prepare($stmt);
    $sql->execute($par);
    $posts['Data'] = $sql->fetchAll();
} catch (PDOException $e) {
    throw new MyEx($e->getMessage());
}

if (count($posts['Data']) > 0) {
    foreach ($posts['Data'] as &$post) {
        $post = Post::addExtra($post);
    }
}