=?Utf-8?B?TEFG?= wrote in
news
The 3 field primary key
absolutely identifies a unique record.
Of course it does: the relevant question is whether than means anything!


By the way, the ID's are aluminum bands placed on the legs of birds.
Banding operations can occur at different sites on the same day, and
the time is when we capture a bird in a mist-net. Several birds can
be caught in a mist-net at the same time.

Here's an entity you haven't mentioned before (ps * always denotes the PK
field, rest are obviously optional):

MistNetDeployments(*Place, *DateAndTime, WhoOrganised,
WeatherAtTheTime, SizeOfNet, etc...)

Place is a FK referencing Places, and DateAndTime is a FK referencing
Events, or whatever you have called your tables.

Many of the tables in the database deal with lots of measurements we
take on the birds.

Catchings(*Place, *DateAndTime, *BirdID, Weight, SignsOfHairloss, etc)

note that the FK is (Place, DateAndTime) references MistNetDeployment, and
there is _no_ (repeat, no) FK referencing Places or Events.

For these tables, just ID and Date-Time are
sufficient as primary key to identify unique records.

To identify what exactly? A record is just somewhere to store some facts
about a Thing or an Event or an Occurrence: it has to mean something in the
real world.


I may be making a mountain out of a molehill, but no book on access
deals with junction tables for more than a single many to many
relationship.

A lot of basic texts deal stop at third normal form; you need to look at
more advanced material for 4, 5, and 6. In the end, though, it still makes
pretty much common sense once you have a feel for what you are actually
modelling.

From what you have said, though, it looks like a couple of 1-M
relationships:

Events ----+
^
MistNetDeployments -- Catchings -- Birds
v
Places ----+


The best advice is always to understand your real life business scenario
first, and then the model falls straight out of that. There is general
theory underlying this, but it's no use until you have your own specifics
nailed down flat.

Hope it helps


Tim F