@Override
	public void prepare(String query) throws SQLException {
		checkCon();
		
		// check if we need to prepare again and reset data from old statements
		if(this.last_prepare.equals(query)) return;
		this.values.clear();
		
		this.stmt = this.con.prepareStatement(query,Statement.RETURN_GENERATED_KEYS);
		this.last_prepare = query;
	}