[AccessD] Many to Many relationship issue

Bill Benson bensonforums at gmail.com
Thu Apr 10 22:33:08 CDT 2014


I think you may be more satisfied storing the contact's details in the
calls table rather than looking them up later. Then you are not in doubt as
to history.

So if the contact changes (eventually they do), New records in the call
table will reflect correct, actual info - not run risk of being improperly
looked up because someone did not update a contact table. In other words i
would consider NOT USING a foreign key to the contact table, just the name
and other details. I might do a select unique rows query from past
transactions for the company in question, while documenting a Call, to get
high probability candidates for who might have been on the current call
(most recently used list)... but I wouldn't rely on a contact Id for this
purpose.

If you later tell the company you spoke to person X you better have your
facts right, and not rely on an update process that might lag.

Does this make sense to you?

It's different if it were a personnel table in your own company, where you
cannot even conduct, let alone document, a transaction prior to having
accurate index values. In a call center context you might be dealing with
"whoever was there at the time, acting as contact" not who you might expect
to be there on a regular basis. I call that characteristic data, it might
not be the right term.
On Apr 10, 2014 10:37 PM, "Jon Albright" <jon.albright at hawaii.rr.com> wrote:

> I did consider the possibility of the contact person changing companies but
> the history at the moment of the phone call, who the person worked for at
> the time of the call and the job it was related to is important.  I figured
> that if the person changed companies, there will just be a new contact with
> the name of this person but there is a notes field in this persons record
> that will record the changes.
>
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Bill Benson
> Sent: Wednesday, April 09, 2014 7:55 PM
> To: Access Developers discussion and problem solving
> Subject: Re: [AccessD] Many to Many relationship issue
>
> Here is my understanding,  it's late and I may be off base.
>
> Many to many relationships are handled by exploiting the separate many to
> one relationships from the component pieces (call - job and call-contact),
> using a cross table.
>
> Your jobcontactcall table is a (often misnamed) "lookup table" but more
> accurately termed a cross table. It needs minimally, a fkcontactid field
> (note: what if it was a conference call with 3 company reps?? Might need
> columns for a callcontact1, callcontact2, callcontact3, etc ) as well as a
> fkjobid field. And what if on the same call you discussed 3 jobs?
> Disgusting stuff...
>
> The contact table has a fkcompanyid field of course. Or you can come at
> company through job as well.
>
> CompanyContacts are a touchy business.
>
> There is the dilemma of storing all contact details even for obsolete
> contact rows, so that details of what happened with whom and where can be
> maintained; yet one doesn't want to assume a contact is still at the
> company
> either. People move all the time, titles change, etc.
>
> Suppose a transaction was created when someone was a project manager. And
> someone else takes on that role. You have to weigh whether you need to know
> they were a project manager at the time of a transaction (or at least
> listed
> as one), versus the need to know what role they are currently occupying so
> as to not call them if they are no longer in that role, yet that role must
> be consulted.
>
> If you just update their role you invalidate the history.
>
> So what you end up with is many contactid values for the same actual
> person,
> preferably only one active at a time. That or keep detailed logs.
>  On Apr 9, 2014 11:59 PM, "Jon Albright" <jon.albright at hawaii.rr.com>
> wrote:
>
> > Hi,  I have a bit of a struggle with this concept.  It's been several
> years
> > that I have done anything with database applications..not since using
> > Foxpro.  Anyway, I work for a contractor and have a need to maintain a
> > customer table (contractor general information), a table for the
> > contact people at the contractor's companies, a projects table (jobs
> > we bid) and a table to log phone calls.  I have the tables created with
> an
> "associate"
> > table for the M2M relationship between the customer table and the jobs
> > table, another "associate" table between the customer contact table
> > and
> the
> > phone calls table.  I also have a one to many created between the
> > customer table and customer contact table.
> >
> >
> >
> > If I create forms for either of the two M2M examples  above, they work
> fine
> > as a standalone but I just can't seem to "tie" the two M2M examples
> > into a functioning arrangement where if you select a company, all the
> > phone calls made by the contact people at the company will display and
> > likewise, if I select a particular job, all the phone calls relating to
> this job display.
> > I have followed an example by Susan Harkins from 2004 that I dug up in
> > a search but am still unable to get beyond the basic.
> >
> >
> >
> >
> >
> > Jon Albright
> >
> > Iniki Enterprises
> >
> > Honolulu, Hawaii
> >
> > (808) 677-7800 x116
> >
> >
> >
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