How to compare data between two tables?

Hi,

My team is trying to develop a SAP data migration tool (DMT) using ABAP.

One of the functionalities in the DMT is to validate the data in the staging area against the loaded SAP data.

The tables in the stagin area are customer tables (i.e. user-defined tables starting with Y, Z).

How do I compare the data in the staging area against data that are loaded into SAP tables? Are there some built-in SAP functions to do this? Or, are there some better ways of doing this (e.g. instead of comparing against data in the SAP tables, we compare with some INTERNAL tables)?

Any help would be greatly appreciated, thanks!