Identify which check box is checked among many check boxes

I want to identify which check box a user is selecting among many other check boxes and then form a SQL statement and execute to modify database.

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Snippet of data storage

(View Image for better understanding)

My existing approach: I've tried storing the position in other variable while printing it but since I'm using loop the variable gets overwritten in every loop.

What I'm thinking: To get SNO and DAY and pass it to function as the user clicks on the checkbox that will create and modify database.

Problem is: I could not get SNO and DAY of the checkbox clicked

Please help as I'm stuck here from three days and it's freaking me out. Thanks in Advance.

PS: I'm using Python 2.7 with Tkinter , if one needs code for my current approach or to view how I'm printing it, please ask

PPS: The entries shown in image are just a part of my complete data where I have many more SNO and DAYs.