Allow Duplicates

i have a table for invoices and at times i receive a duplicate invoice number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from a
different country?

Thanks

Hi,

I always take an autonumber field as PK field. You can then create another
unique index on the combination of the invoice number field and the country
field
--
Kind regards
Noëlla


"acss" wrote:

i have a table for invoices and at times i receive a duplicate invoice number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from a
different country?

Thanks

In message , acss
writes
i have a table for invoices and at times i receive a duplicate invoice number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from a
different country?

I'm assuming that InvoiceID is not an autonumber field.

Open the table in design view. Select both the InvoiceID and Country
fields (by shift- or Ctrl-clicking.) Click on the Primary Key button.
You should see the key symbol beside both of the fields.


--
Bernard Peek

You are correct that it is not autonumber and is unique though duplication
happens from time to time dependant on country submitting invoices and still
need to be recorded regardless. I am receiving the error that there is
already a relationship so i must delete it before assigning these two keys.
Thanks

"Bernard Peek" wrote:

In message , acss
writes
i have a table for invoices and at times i receive a duplicate invoice number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from a
different country?

I'm assuming that InvoiceID is not an autonumber field.

Open the table in design view. Select both the InvoiceID and Country
fields (by shift- or Ctrl-clicking.) Click on the Primary Key button.
You should see the key symbol beside both of the fields.


--
Bernard Peek

If your Invoices table takes part on the primary key side of one or more
relationships, then I don't think the multi-field PK is a good idea. It
would mean that you have to add the Country field to the foreign key(s) in
the other table(s) as well, which could make a larger headache for you.

Also, since a field in a PK cannot be null, you would need to ensure ALL of
your records had a value in the Country field.

I suggest you go with Noëlla's idea and add an Autonumber field - InvoiceID.
(If your existing field is already called InvoiceID then rename it to
InvoiceNum or suchlike - I prefer to reserve the "ID" suffix for autonumber
fields as an aid to documentation).

After adding the autonumber field, save the table (but don't try to change
the primary key yet). Then edit the design of your related table(s) and add
a long integer field "InvoiceFK" for the foriegn key.

Now create an update query to populate the new field. Its SQL will look
something like this:

UPDATE [InvoiceTable] INNER JOIN [OtherTable] ON
[InvoiceTable].[InvoiceNum] = [OtherTable].[OldForeignKeyField]
SET [OtherTable].[InvoiceFK] = [InvoiceTable].[InvoiceID];

Then you can remove the old relationship, then change your PK to InvoiceID
and add a new relationship joining the two new fields.

Finally, you can add a composite index for the two fields, InvoiceNum and
Country, and delete the old FK field from the other table.

--
Good Luck :-)

Graham Mandeno [Access MVP]
Auckland, New Zealand

"acss" wrote in message
...
You are correct that it is not autonumber and is unique though duplication
happens from time to time dependant on country submitting invoices and
still
need to be recorded regardless. I am receiving the error that there is
already a relationship so i must delete it before assigning these two
keys.
Thanks

"Bernard Peek" wrote:

In message , acss
writes
i have a table for invoices and at times i receive a duplicate invoice
number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from
a
different country?

I'm assuming that InvoiceID is not an autonumber field.

Open the table in design view. Select both the InvoiceID and Country
fields (by shift- or Ctrl-clicking.) Click on the Primary Key button.
You should see the key symbol beside both of the fields.


--
Bernard Peek

Hello,
I am still working on this and i am curious as to how you create a unique
index on a combination of invoice and country field? The primary key is the
invoice number as an autonumber so the table can not have more than one
primary key....can you eloborate for me please?

"Noëlla Gabriël" wrote:

Hi,

I always take an autonumber field as PK field. You can then create another
unique index on the combination of the invoice number field and the country
field
--
Kind regards
Noëlla


"acss" wrote:

i have a table for invoices and at times i receive a duplicate invoice number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from a
different country?

Thanks

Hi Joe (?)

I'm confused. You say "The primary key is the invoice number as an
autonumber" but you also said that the invoice number was in the imported
data, so it can't be an autonumber!

I suggest you add a new autonumber field named InvoiceID and make that your
primary key. Then, make InvoiceNumber and Country both required fields and
make them a composite unique key.

To do this, open the Indexes window (ViewIndexes) and in the first blank
row, enter "InvoiceNumberCountry" as the index name and select InvoiceNumber
as the field name. Then, in the index properties below, change Unique to
"Yes". Now, in the next blank line, choose Country as the field name (but
leave index name blank).

--
Good Luck :-)

Graham Mandeno [Access MVP]
Auckland, New Zealand


"acss" wrote in message
...
Hello,
I am still working on this and i am curious as to how you create a unique
index on a combination of invoice and country field? The primary key is
the
invoice number as an autonumber so the table can not have more than one
primary key....can you eloborate for me please?

"Noëlla Gabriël" wrote:

Hi,

I always take an autonumber field as PK field. You can then create
another
unique index on the combination of the invoice number field and the
country
field
--
Kind regards
Noëlla


"acss" wrote:

i have a table for invoices and at times i receive a duplicate invoice
number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from
a
different country?

Thanks

Apologies for the confusion Graham,

I would like for the primary key to be unique in the invoice table and as a
foreign key in the details Table however i have the challenge that duplicate
invoices need to be entered and should be accepted only if it is from a
different country.

InvTable
InvID---PK
InvCtry
Invdate
etc

InvDetails
InvID-FK
ProductID--FK---COMPOSITE KEY consisting of InvID and ProductID
Price
Qty

ProductTable
ProductID-----PK-Autonumber
ProductName
Category
Etc

I am stuck since i need a one to many relationship between Inv and
details(one invoice can have many details).The problem occurs as the same
invoice number needs to be entered 3 times once for china another for ecuador
and another for brazil..that is why i need acess to accept same invoice
number only if by different countries. Can you suggest some direction please?

Thanks,


"Graham Mandeno" wrote:

Hi Joe (?)

I'm confused. You say "The primary key is the invoice number as an
autonumber" but you also said that the invoice number was in the imported
data, so it can't be an autonumber!

I suggest you add a new autonumber field named InvoiceID and make that your
primary key. Then, make InvoiceNumber and Country both required fields and
make them a composite unique key.

To do this, open the Indexes window (ViewIndexes) and in the first blank
row, enter "InvoiceNumberCountry" as the index name and select InvoiceNumber
as the field name. Then, in the index properties below, change Unique to
"Yes". Now, in the next blank line, choose Country as the field name (but
leave index name blank).

--
Good Luck :-)

Graham Mandeno [Access MVP]
Auckland, New Zealand


"acss" wrote in message
...
Hello,
I am still working on this and i am curious as to how you create a unique
index on a combination of invoice and country field? The primary key is
the
invoice number as an autonumber so the table can not have more than one
primary key....can you eloborate for me please?

"Noëlla Gabriël" wrote:

Hi,

I always take an autonumber field as PK field. You can then create
another
unique index on the combination of the invoice number field and the
country
field
--
Kind regards
Noëlla


"acss" wrote:

i have a table for invoices and at times i receive a duplicate invoice
number
from another country. How do i set up a primary key (InvoiceID) and a
secondary key (country) that would allow a duplicate entry only if from
a
different country?

Thanks

On Tue, 4 Aug 2009 18:34:01 -0700, acss wrote:

Apologies for the confusion Graham,

I would like for the primary key to be unique in the invoice table and as a
foreign key in the details Table however i have the challenge that duplicate
invoices need to be entered and should be accepted only if it is from a
different country.

InvTable
InvID---PK
InvCtry
Invdate
etc

InvDetails
InvID-FK
ProductID--FK---COMPOSITE KEY consisting of InvID and ProductID
Price
Qty

ProductTable
ProductID-----PK-Autonumber
ProductName
Category
Etc

I am stuck since i need a one to many relationship between Inv and
details(one invoice can have many details).The problem occurs as the same
invoice number needs to be entered 3 times once for china another for ecuador
and another for brazil..that is why i need acess to accept same invoice
number only if by different countries. Can you suggest some direction please?

It sounds like you need a composite, two-field primary key (InvoiceNo and
CountryCode), which will also require a composite, two-field foreign key in
the details table. You can use

InvCtry;InvID

as the Master Link Field and Child Link Field property of your subform.

You will not be able to use an Autonumber for InvID, but then it's
inappropriate to use an autonumber for that purpose in any case.
--

John W. Vinson [MVP]

My understanding was exactly correct then, and my suggestion still stands:

I suggest you add a new autonumber field named InvoiceID and make that
your
primary key. Then, make InvoiceNumber and Country both required fields
and
make them a composite unique key.

Your tables would then look like this:

InvTable
--------
InvID---PK - Autonumber
InvNum (as imported - used to be InvID)
InvCtry
Invdate
etc

InvDetails
----------
InvID-FK (long numeric related to the *new* InvID)
ProductID--FK---COMPOSITE PK consisting of InvID and ProductID
Price
Qty

Add a composite unique key comprising InvNum and InvCtry as I described
yesterday.

John V has suggested another alternative which is to add InvCtry to
InvDetails and have a two-field relationship. This is perfectly valid, but
my preference is (a) to avoid multi-field relationships as they can become
terribly messy and (b) to avoid using imported data as primary keys. The
reason for (b) is that you never know when the rules are going to change -
for example, your invoice number might be a numeric field and then the head
office in Brazil decides to use alpha characters in its invoice numbers, so
you need to change the data type in several places, not just one, and
destroy and recreate relationships. Or perhaps in China they decide that
they will reuse invoice numbers starting at the beginning of each year, so
you need to add another field (InvYear) to your PK and also add it to your
related tables.

--
Good Luck :-)

Graham Mandeno [Access MVP]
Auckland, New Zealand

"acss" wrote in message
...
Apologies for the confusion Graham,

I would like for the primary key to be unique in the invoice table and as
a
foreign key in the details Table however i have the challenge that
duplicate
invoices need to be entered and should be accepted only if it is from a
different country.

InvTable
InvID---PK
InvCtry
Invdate
etc

InvDetails
InvID-FK
ProductID--FK---COMPOSITE KEY consisting of InvID and ProductID
Price
Qty

ProductTable
ProductID-----PK-Autonumber
ProductName
Category
Etc

I am stuck since i need a one to many relationship between Inv and
details(one invoice can have many details).The problem occurs as the same
invoice number needs to be entered 3 times once for china another for
ecuador
and another for brazil..that is why i need acess to accept same invoice
number only if by different countries. Can you suggest some direction
please?

Thanks,


"Graham Mandeno" wrote:

Hi Joe (?)

I'm confused. You say "The primary key is the invoice number as an
autonumber" but you also said that the invoice number was in the imported
data, so it can't be an autonumber!

I suggest you add a new autonumber field named InvoiceID and make that
your
primary key. Then, make InvoiceNumber and Country both required fields
and
make them a composite unique key.

To do this, open the Indexes window (ViewIndexes) and in the first blank
row, enter "InvoiceNumberCountry" as the index name and select
InvoiceNumber
as the field name. Then, in the index properties below, change Unique to
"Yes". Now, in the next blank line, choose Country as the field name
(but
leave index name blank).

--
Good Luck :-)

Graham Mandeno [Access MVP]
Auckland, New Zealand


"acss" wrote in message
...
Hello,
I am still working on this and i am curious as to how you create a
unique
index on a combination of invoice and country field? The primary key is
the
invoice number as an autonumber so the table can not have more than one
primary key....can you eloborate for me please?

"Noëlla Gabriël" wrote:

Hi,

I always take an autonumber field as PK field. You can then create
another
unique index on the combination of the invoice number field and the
country
field
--
Kind regards
Noëlla


"acss" wrote:

i have a table for invoices and at times i receive a duplicate
invoice
number
from another country. How do i set up a primary key (InvoiceID) and
a
secondary key (country) that would allow a duplicate entry only if
from
a
different country?

Thanks