using single gridview to display many tables from SQL

Question

Hi friends,

I have city_master,country_master etc tables in sql. I am loading data from these tables based on selection made (ie if city is selected data from city_master/if country is selected data from country_master) will be displayed. I also have to insert data,update,deleted from Gridview. Want to write methods in a .cs file to handle this. But not getting an idea how to do as i am just a beginner and not strong in OOPS. Plzz help

Have attached the file  .. plzz help