parametizes scope.

gistfile1.txt

public function allInCategory($categoryIds){
			$this->getDbCriteria()->mergeWith(array(
					'with' => array(
						'courseCategories' => array(
							'condition' => 'categoryID in (:categoryIds)'
							)
						),
					'params' => array(':categoryIds' => $categoryIds),
				));
			return $this;
		}