public void linkTwoTables(String tableName, String firstCol, String secondCol, String firstKey, String secondKey){
		// if link is not yet established
		if (!isLinkEstablished(tableName, firstCol, secondCol, firstKey, secondKey)){
			String query = "INSERT INTO "+tableName+" VALUES ('"+firstKey+"' , '"+secondKey+"');";
			try {
				Statement stmt = con.createStatement();
				stmt.execute(query);
			} catch (SQLException e) {
				logger.warn("Invalid query: "+ query, e);
				e.printStackTrace();
			}
		}
		
	}