Thanks Fred, I have answered each part below:

"Fred" wrote:

Kate,

As a side note, your "changing doctor(GP)" note implies that the doctor's
name is a part of your mission/question, but you didn't tell us anything
about that.

As with address, I need to know who their family doctor was at the time of
the test as the causes of the infection could relate to treatment given.
Therefore I thought this could be done in a similar way - or even in the same
table?!

Another question: Do your have a requirement for recording a then-current
address for each test? Let's assume not.

I need the address at the time of the test - if they were in a nursing home
there could've been an outbreak and that info would be lost if the patient
then went back home and the address overwritten.

Also, a cornerstone of this will be to have each patient uniquely /
correctly identified with a number, and have only one "patient" entry for
eadch patient. You have described a path you are taking to that point.
Let's assume that you have already accomplished this.

The this is going to have to start with you making a decision between Plan
"A" and plan"B". "B" is more work; you need to decided if it is necessary
or sufficiently useful to retain previous addresses.

Going to have to go with something along the lines of Plan B!

Plan "A": Just keep a single address in the patient record/table, and keep
it current.

Plan "B" Make a second address table, and link it's entries to the patient
table on a PatientIDNumber field. Include a "CurrentLocation" field where
entery of a ""Y" (Yes) indicatres that that is their current address.

Hope that helps a little.

Fred