>There are about 56 fields for the
>financial and 40 fields for the
>persons data.
Then, it seems to be that splitting the data in two tables (in a one-to-one relationship) will be a very good idea.

>Doesn't data normalization require one table
>if two tables would have a one to
>one relationship?
I am 100% sure what the purists will argue here. Yet, from the practical point of view, in you scenario it makes sense to have two tables with a 1-1 relationship.

> I heard that you should make child tables
> only if there is a one to many relationship
> present.
That is correct. Yet, I don't think a 1-1 relationship qualifies as a "parent-child" relationship.


>Which practical advantage would it make
> to make child tables with a one to one
> relationship?
Advantages:
* It makes sense to split the data in two tables to mimic its nature.
* Some DBMS perform better when tables have few columns (narrow tables) than with very wide tables (with many columns.)

Disadvantages
* You need to code to logic to add/remove records in both tables.