public boolean addAttr(String col, String table){
		String s = col + " @ " + table;
		s = s.toLowerCase();
		if(attr.containsKey(s)){
			int val = attr.remove(s);
			attr.put(s, val + 1);
			return false;
		}
		else{
			attr.put(s, 1);
			return true;
		}
	}