Android connect to sqlite db from sidebar fragments

sample screen

I'm on application which is in the above picture... and i need to do operations with sqlitedb on click of options shown in navigation bar... but when i click on option the context to dbhelper is always MainActivity regardless the fragment.. when i click on 1st option then context is MainActivity when i click on 2nd option then context is MainActivity
I'm unable to perform operations on db..
please do help me