public void addOffering(String offering_id, String offering_name){
		// only add phenomenon to database if not yet added
				if (!this.isOfferingInDatabase(offering_id)) {
					String query = "INSERT INTO offering VALUES ('" + offering_id+"','"+offering_name+"');";
					try {
						Statement stmt = con.createStatement();
						stmt.execute(query);
					} catch (SQLException e) {
						logger.warn("Invalid query: "+ query, e);
						e.printStackTrace();
					}
				}
	}