Using files as dbase

Hello,
first, sorry for long thread;

i'm asking if there are examples or tutorials to show how to use files with Arduino Mega as a small data base, I need to store RFID card numbers with date and time then retrieve them again according to user defined criteria, i.e. from date to date or card number. that's for logger.

Which is more applicable! open one file for each card number like 0123456.txt, contains user data like name and job title or to use one file for all card numbers i.e....

Using files as dbase

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