Windows Batch Script for 2 Cases

I use the following .bat script

set varSearch="C:\Users\User1\Desktop\Test-folder\*.crypt8"
for /f %%i in ('dir %varSearch% /B ') do set varSearch= %%i
WhatsAppViewer.exe -decrypt8 %myName% key exp.db

sqlite3.exe exp.db<command.txt
cd C:\xampp\mysql\bin
mysql -u admin -p1234 < query.txt

The basic function is to find a file thats ending with .crypt8, decrypt it, save as csv and import to mysql. Its working correctly

But i need some extra features

Case1

The folder contains more than 1 file, and every file has to be processed, but only once

Case 2

Everyday at least one file gets added. It would be superb if the .bat could be scheduled as a task, and run every night and just process the new added files.

Does anybody has a solution for this?