(Msg. 25) Posted: Wed Jul 30, 2008 8:33 am
Post subject: RE: Database Design Normalization help [Login to view extended thread Info.] Archived from groups: microsoft>public>access>tablesdbdesign (more info?)
I am still confused...I tried Access help and found this:
"An index is a Microsoft Access feature that speeds up searching and sorting
in a table." Okay, I get this.
"You can create an index for a field in the Indexes window (Indexes window:
In an Access database, a window in which you can view or edit a table's
indexes or create multiple-field indexes.) Okay, would it have been too much
to show a picture of what the window looks like, or how to get to that
window??? Do they simply mean when you open your table in design view? (On
top you have field name and datatype, on the bottom General and lookup tab?)
of table Design view (Design view: A window that shows the design of these
database objects: tables, queries, forms, reports, macros, and data access
pages. In Design view, you can create new database objects and modify the
design of existing ones.), or by setting the field's Indexed property to Yes."
So do you mean that each field in a table (or query etc) has the possibility
of being indexed? You could use one field and index it. Or you could have
more than one field, and therefore indexes.
If so, here is where I am confused:
When you view the indexes in your table design view (OK at this point) you
have the opportunity to select more than one field (okay to this point) and
provide a single name for the index. What do you mean by provide a single
name for the index---the Table name?
Sorry Duane, I hope you are not pulling your hair out, but I really need to
undestand this basic stuff correctly, as I am mostly following a recipe right
now---I know I need to make a cake, that it has ingredients, they have to get
mixed in certain relationships, etc etc...but I still do not have the reasons
for baking etc down pat!
BTW, if you answer, "Did someone say cake?" I would not blame you ! ;-]
Billiam
"Duane Hookom" wrote:
> When you view the indexes in your table design view, you have the opportunity
> to select more than one field and provide a single name for the index. You
> can set these indexes to not allow duplicates. This is an alternative to the
> single field primary key. I usually create a single field primary key and a
> unique index on the other foreign key fields.
>
> "Billiam" wrote:
>
> > Sorry, Duane, I am not sure what you meant by "You can create a unique index
> > on a combination of the InstructorID and AddressID." as stated a few threads
> > back...
> > I am not sure if you were offering another way to index the junction table,
> > or ? Sorry, I am really new to this, and sometimes all the reading I've done
> > just makes you more confused!
> >
> >
> > "Duane Hookom" wrote:
> >
> > > I almost always create a single primary key field in a table which is
> > > generally an autonumber. I do this because I create lots of web pages and I
> > > would like to pass the value of a single field to a web page for editing a
> > > single record.
> > >
> > > You could remove the autonumber primary key in a small junction table if you
> > > want and replace it with the combination of the two fields. I wouldn't
> > > because I am lazy (consistently lazy > > > --
> > > Duane Hookom
> > > Microsoft Access MVP
> > >
> > >
> > > "Billiam" wrote:
> > >
> > > > Yes, now the relationships are one to many, thanks!
> > > >
> > > > "Duane Hookom" wrote:
> > > >
> > > > You can create a unique index on a combination of the InstructorID and
> > > > AddressID.
> > > >
> > > > To clarify,does this mean I do not need the InstructorAddressesID as the
> > > > Primary key in tblInstructorAddresses? And if so, does this also mean that
> > > > the InstructorID and AddressID foreign keys combo make up the primary key of
> > > > tblInstructorAddresses as a composite key?
> > > >
> > > > Billiam
> > > > > "Billiam" wrote:
> > > > >
> > > > > > Thanks for your help so far Duane, I really appreciate it !!!!
> > > > > >
> > > > > > It seems that while I may understand that a many to many relationship is
> > > > > > resolved by using an intermediate table or Junction table, with each entity
> > > > > > on the one side of a many relationship to the junction box, my relationship
> > > > > > diagram does not reflect that...which leads me to thinking I am not doing
> > > > > > something correctly.
> > > > > > Can you tell me if this is the correct procedure for the following many to
> > > > > > many realtionship?
> > > > > >
> > > > > > tblInstructors
> > > > > > instructorID (PK, autonumber, Long Integer, Yes Index NO Duplicates,ref.
> > > > > > integrity enforced)
> > > > > > Instructor ID# (starts with zeros so a text field)
> > > > > > FirstName
> > > > > > Midname
> > > > > > Lastname
> > > > > >
> > > > > > tblAddresses
> > > > > > AddressID (PK, autonumber, Long Integer, Yes Index NO Duplicates,ref.
> > > > > > integrity enforced)
> > > > > > AddressLine1
> > > > > > AddressLine2
> > > > > > AddressLine3
> > > > > > City
> > > > > > ProvinceStateCounty
> > > > > > PostalCode
> > > > > > Country
> > > > > >
> > > > > >
> > > > > > tblInstructorAddresses
> > > > > > InstructorAddressID (PK, autonumber, Long Integer, Yes Index NO
> > > > > > Duplicates,ref. integrity enforced)
> > > > > > InstructorID (FK, Index Yes No duplicates, JOIN Type 1)
> > > > > > AddressID (FK, Index Yes No Duplicates JOIN Type 1)
> > > > > >
> > > > > > As you can see from my relationship report, InstructorID in tblInstructors
> > > > > > is realted one to many with InstructorID in tblInstructorAddresses. It is my
> > > > > > understanding that this is how every many to many realtionship is resolved.
> > > > > > You will note, however, that AddressID from tblAddresses realtes to AddressID
> > > > > > in tblInstructorAddresses as a one to one---not a one to many as I suspect it
> > > > > > should. Why is this happening, Duane? (BTW, I create the realtionship by
> > > > > > taking the primary ID from the table and dropping it on top of the
> > > > > > foreignkeyiD in the junction/intermediate table.)
> > > > > >
> > > > > > The really odd thing is that when i click on edit the relationship for
> > > > > > Instructor to instructoraddress it says it is a one to one relationship
> > > > > > between the instructorID's, however, the diagram clearly shows it as a one to
> > > > > > many relationship! Man am I confused!
> > > > > >
> > > > > > Billiam
> > > > > >
All times are: Eastern Time (US & Canada) (change) Goto page Previous1, 2, 3, 4
Page 4 of 4
You can post new topics in this forum You can reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum