help with PDO error

[traq]

Hi, I'm brand new to PDO, so I would appreciate all the help I can get. I'm using PDO to query a SQLite database I set up earlier for testing. I am getting an error that says,

Warning: Invalid argument supplied for foreach() in (path removed) on line 38

line 38 is highlighted below. I have been rewriting it for about an hour now.

try {
    $dbh = new PDO("sqlite:".$_SERVER['DOCUMENT_ROOT']."/reel/demo/a.sqlite");
    echo "Connected again";
    $sql = "SELECT * FROM moulding";
    foreach ($dbh->query($sql) as $row){
        //line 38 below
        echo $row['part'] .' '. $row['size'] .' '. $row['type'] .' '. $row['species'];
      }
      $dbh = null;
    } catch (PDOException $e) {
      print "Error!: " . $e->getMessage() . "<br/>";
      die();
    } 

thanks in advance, everyone

Edit:
I got part of it figured out. The argument was invalid because the try{} block above it was not successfully creating the table and inserting the records. I've got it working with a different DB I built using SQLite manager. I would however, appreciate some advice on how to fix the first block (below) to update my DB via PHP:

try {
  $dbh = new PDO("sqlite:".$_SERVER['DOCUMENT_ROOT']."/reel/demo/a.sqlite");
  echo "Connected\n";
  $dbh->exec("CREATE TABLE moulding(part varchar(10) primary not null, size varchar(25) not null, type varchar(25) not null, species varchar(25) not null)");
  $count = $dbh->exec("INSERT INTO moulding (part, size, type, species) VALUES (1060, '19/6 x 4', 'base', 'cherry')");
  echo $count;
  $dbh = null;
} catch (Exception $e) {
  echo "Failed: " . $e->getMessage();
} 

Edit: sorry, guys. I just stepped into PDO last night, and I really expected it to be harder. I'm sure I'll have a real problem soon enough, though, so 'till then...
peace out, and thanks