如何根据internet连接在不同的数据库中保存数据

I want to make my code to be able to check if internet connection is established. After that I will normally save records in the database on the server, but I want to be able to save records in the local database on pc everytime the connection is lost and before every normal connection on the server check if the local database is empty and copy everything from local database to server database.I want to make my code to be able to check if i