Hi,
I want to use a database for log control process information and I must
to store this info in event format:

Timestamp: Event timestamp
OID: Event object source id
oldvalue: Old value of object property
newvalue: Old value of object property


The problem consists on the values can be:

- Integers
- Floats
- Booleans
-....

How I can to model this kind of polimorphism ? In OO world it can be solved with a class hierarchy (extends), but I don't know how can i to solve this problem in ER paradigm

Thanks...