Tracking changes in data - "validating" data base

I need to revise the structure of a data base application
that I have developed, so that the application can
be "validated". One part is that I need a way
to "freeze" initial data entered by user (this is medical
information), identifying user, and which allows the data
to be changed later, but only where the identity of user
making the change and what the previous value for the
data was can be accessed -- ie, tracking any changes made
in the data.

Any experience or suggested resources to study to develop
this would be most appreciated.
Thanks.
Bob Ratner

As stated in another group (please don't post to multiple groups - wastes
too many people's time)...

Do a search. Tracking changes has been asked and answered hundreds of
times. Search before asking your questions.

Rick B


"Bob Ratner" wrote in message
...
I need to revise the structure of a data base application
that I have developed, so that the application can
be "validated". One part is that I need a way
to "freeze" initial data entered by user (this is medical
information), identifying user, and which allows the data
to be changed later, but only where the identity of user
making the change and what the previous value for the
data was can be accessed -- ie, tracking any changes made
in the data.

Any experience or suggested resources to study to develop
this would be most appreciated.
Thanks.
Bob Ratner