write a code for sqlite on c++ on esp32 -- 2

I have designed the code which stores the data say temp and humidity, in the database I created, and simultaneously sending the values, to the server via wifi. Now I want a code which extract only that values from data base and send to the server which were saved during, when the device were offline and send to the server. And also mark those values as sended in the data base. Sending the values to the server is optional, main task it to extract only those values which are being saved only during when device was offline and marking them sended or any thing else in the database. checking the online /offline status is also optional and not required.
The delivered code should be properly commented.
Thanks