Thread: redo my design
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Old April 18th, 2010, 09:15 PM posted to microsoft.public.access.gettingstarted
John W. Vinson
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Posts: 18,261
Default redo my design

On Sun, 18 Apr 2010 10:04:01 -0700, shumate62
wrote:

So, I made the three tables as suggested, tblPerson, Tbl PersonGroup,
TblGroup and then tried to create the relationship for them but it's stuck on
only having a one to many relationship, which of course it isn't it's a many
to many (there are multiple authors, and people belong to more than one
group) did I do something wrong in the formatting of the tables that blocked
it from being a many to many?


There IS NO SUCH THING as a many to many relationship in the table relations
window. The only relationships you can see in the window are indeterminate,
one to one, one to many; the first is useless and the second is legitimate but
pretty rare.

A many to many relationship *consists* of two one to many relationships.

Each tblPerson record is related to many tblPersonGroup records - a one to
many relationship. Each tblGroup record is related to many tblPersonGroup
records - another one to many. tblPerson is only related to tblGroup *by way
of these two one to many relationships* - it's indirect; each record in
tblPersonGroup encodes the information that one particular record in tblPerson
is related to one particular record in tblGroup. If there are many connections
between the two tables, each such connection is stored in a different record
in tblPersonGroup.
--

John W. Vinson [MVP]