Good personal pie. I need to save data from the mq135 gas sensor in the mysql database. I am using xamp with php. I have all the code for the temperature and humidity sensor being sent to the database.
Sorry for the late reply, but as far I know, you need some connection between the sensor and the PC that contains the local server, unless you want to do it remotely with some prototyping board with WiFi connection.
If you are doing it with a serial connection to the PC, you could make some python script in order to pre-process the data and then write to the SQL database using SQLAlchemy.