Form-subform links - am I breaking the rules?

[Mike Heden]

What are the rules regarding the linking fields between a form and
subform? Does the field on the main form *have* to be based on a
primary key?

Most examples seem to quote the use of a primary key on the main form,
but I've seen one or two places where it's implied that this doesn't
have to be the case - references in the help file to 'normally' using
a primary key, etc.

For various historical reasons I find myself having to associate a
subform to its parent using a field that isn't unique in the table on
which the main form is based. However, due to the way the main form
works, that data *will* be unique within the master form's recordset
at all times.

It appears to work in practice...

Can anyone confirm that this is a legitimate approach to take, given
that I can't use a primary key.

Thanks,

Mike

[Don Leverton]

Hi Mike,

I'm not sure that it *has* to be the PK either. I believe that in most cases
that it *should* be, and that perhaps you may want to look at your table
structure to see if you might be going around it the wrong way. If data from
one table relates to data in another, there should be a way to join them. It
may require a join table to complete a many-to-many relationship for
example.

I do know that I've had a couple of occasions where I want to "auto-fill"
more than one field in my subform. I had figured out that the
LinkMaster/LinkChild automatically did this for one field, so I thought
"what the heck" ... and tried using a 2-field join. You can "pair" them by
simply adding a semi-colon between them, but the quantity and order of the
fields must remain the same. Both fields in the subform do get auto-filled.
--
HTH,
Don
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"Mike Heden" <mh****@bigfoot.com> wrote in message
news:53*************************@posting.google.co m...

What are the rules regarding the linking fields between a form and
subform? Does the field on the main form *have* to be based on a
primary key?

Most examples seem to quote the use of a primary key on the main form,
but I've seen one or two places where it's implied that this doesn't
have to be the case - references in the help file to 'normally' using
a primary key, etc.

For various historical reasons I find myself having to associate a
subform to its parent using a field that isn't unique in the table on
which the main form is based. However, due to the way the main form
works, that data *will* be unique within the master form's recordset
at all times.

It appears to work in practice...

Can anyone confirm that this is a legitimate approach to take, given
that I can't use a primary key.

Thanks,

Mike