Test-Automation: Diff Data in Oracle Database - what are best practices?

We're re-writing a COBOL application in Java. We want to make sure, the applications behave the same, by validating our unit tests produce the same DB changes. How can we easily diff the data in the DB to a given master-DB (e.g. the Database in which the COBOL program has written data). We want to do this in an automated way. Bonus: Is it possible to exclude several columns like date columns in a comparison?