Comma-separated list of related item IDs

I'm trying to return an array or comma-separated list of related item IDs (as determined by the Item Relations plugin) but the following is giving me only the first related item id. What am I missing?

function related_items_query($item_id=null){
	if ($item_id){

		$db = get_db();
		$sql='SELECT object_item_id FROM omeka_item_relations_relations WHERE subject_item_id LIKE '.$item_id;

		$result = $db->query($sql);

		if($count=$result->rowCount()){

			$ids=$result->fetch();

			return implode(', ', $ids);

		}
	}
}

fetch() only fetches one row.

You probably wanted to use fetchAll(). Additionally, since it looks like you just want a single value from each row, you want to use the Zend_Db::FETCH_COLUMN mode.

Just caught the fetchAll() part. I'll look into FETCH_COLUMN. Thanks!

function related_items_query($item_id=null){
	if ($item_id){

		$db = get_db();
		$sql='SELECT object_item_id FROM omeka_item_relations_relations WHERE subject_item_id LIKE '.$item_id;

		$result = $db->query($sql);

		if($count=$result->rowCount()){

			$ids=$result->fetchAll();
			$relations=array();
			for($i = 0; $i < $count; $i++){
				$relations[]=$ids[$i]['object_item_id'];
			}
			return implode(', ',$relations);

		}
	}
}