Pulling Variable to Use

Hi, back with another stupid question! So I wrote an Execute Query that should return a value or a null. Regardless, I want it to save that result so that I can check if it is null or has data. If it has data, then I want to start a process. Can you help me to store the variable and then do the check on that?

The goal is to check a database and if my job is completed, I want to open an Excel Macro.

Thank you!

var - result stored after query execution
use if activity :
condition - var is nothing

Thank you Nilay. Can you help me understand how to get to the stored Var from the query execution? Do I need to put it in the Output DataTable or does it go to one?

Please know that I am doing all this self discovering.