One-To-One Tables

This may prove to be an open-ended question, but here goes. I'm anticipating
having three tables with one-to-one relationships back to another table. All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

More info: The main table is Agreements. The sub-tables are Requirements,
Certificates, and Validations. Each Agreement imposes a set of Requirements.
A Certificate lists what is being offered to meet those Requirements, and a
Validation checks what is being offered against what is being required, field
by field.

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There is
truth in both statements as all of these are interrelated. I'm just afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out that
despite all your caution you made the wrong choice.

Seems to me if an Agreement imposes a set of Requirements, then you have a
One-to-Many relationship. Is this correct? Hopefully you aren't putting
Requirements in a table with fields something like Req1, Req2, and so on.
--
Jerry Whittle, Microsoft Access MVP
Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder.


"oldblindpew" wrote:

This may prove to be an open-ended question, but here goes. I'm anticipating
having three tables with one-to-one relationships back to another table. All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

More info: The main table is Agreements. The sub-tables are Requirements,
Certificates, and Validations. Each Agreement imposes a set of Requirements.
A Certificate lists what is being offered to meet those Requirements, and a
Validation checks what is being offered against what is being required, field
by field.

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There is
truth in both statements as all of these are interrelated. I'm just afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out that
despite all your caution you made the wrong choice.

On Tue, 25 Aug 2009 10:59:01 -0700, oldblindpew
wrote:

This may prove to be an open-ended question, but here goes. I'm anticipating
having three tables with one-to-one relationships back to another table.

One to one relationships are VERY rare. See below.

All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

If the reality is that there is a "master" table and two "Child" tables, then
relate each child to the master. If the third table logically relates to data
in the second table, then cascade. It depends on the logical structure of the
data.


More info: The main table is Agreements. The sub-tables are Requirements,
Certificates, and Validations. Each Agreement imposes a set of Requirements.

But a one to one relationship implies that an Agreement can have zero or one
Requirement, never more. Are you perhaps using one *FIELD* per requirement? If
so you're not normalized.

A Certificate lists what is being offered to meet those Requirements, and a
Validation checks what is being offered against what is being required, field
by field.

Not record by record, using a one to many relationship?

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There is
truth in both statements as all of these are interrelated. I'm just afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out that
despite all your caution you made the wrong choice.

Just be sure you don't have repeating groups, to start with! Perhaps you could
post (real or hypothetical) sample data and indicate the field structures of
your tables.
--

John W. Vinson [MVP]

Thanks for your reply. I don't think the one-to-many is correct. It is true
that one Agreement imposes many requirements, however, the requirements
consist of a standard set of categories. There will be a set group of fields
making up the Requirements Table, with the values in those fields varying
from one Agreement to the next.

This is really about subcontractor's insurance, but to simplify, let's say
we're talking about furnishing cars. One Agreement may require a Yellow,
2-door, Chevy. Another Agreement may require a Red, 4-door, Ford. The
Requirements table would have fields for Color, Number of Doors, and Make.
Field values would be dictated by each Agreement. A Certificate would be
furnished describing the actual car being offered in fulfillment of the
Agreement. The Validation would show how close a match was achieved between
the Requirement and the Offering.


"Jerry Whittle" wrote:

Seems to me if an Agreement imposes a set of Requirements, then you have a
One-to-Many relationship. Is this correct? Hopefully you aren't putting
Requirements in a table with fields something like Req1, Req2, and so on.
--
Jerry Whittle, Microsoft Access MVP
Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder.


"oldblindpew" wrote:

This may prove to be an open-ended question, but here goes. I'm anticipating
having three tables with one-to-one relationships back to another table. All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

More info: The main table is Agreements. The sub-tables are Requirements,
Certificates, and Validations. Each Agreement imposes a set of Requirements.
A Certificate lists what is being offered to meet those Requirements, and a
Validation checks what is being offered against what is being required, field
by field.

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There is
truth in both statements as all of these are interrelated. I'm just afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out that
despite all your caution you made the wrong choice.

Thanks for your reply. See also my response to Jerry Whittle.

This is about Certificates of Insurance furnished by subcontractors. Much
of my design is driven by the standard certificate form commonly seen in the
industry. This certificate form has lots of fields on it, and in order to
validate the certificate, each field has to be checked. My approach has been
to create one table for the certificate information and another similar table
to store the results of the validation, if ever I can get there.

To check or validate the certificate, there must be requirements to check
against. Originally I had a third table consisting of three records defining
three standard sets of insurance requirements, because we took sort of a
"Small, Medum, Large" approach to our requirements. Each Agreement pointed
to one of these three standard sets of requirements. But since it is
possible for any given agreement to modify or waive any given insurance
parameter, it seems better to let each agreement have its own unique set of
insurance requirements. Thus I arrive at three tables each relating back to
the Agreements table in a one-to-one fashion.

In order to ease the task of establishing the insurance requirements for
each agreement, I'll need to figure out how to enable the user to copy a
requirements record from one of the three standards, or from an existing
agreement, and then make whatever modifications may be called for by the
Agreement.

I appreciate your taking time to consider this and offer advice on whether
it matters how the tables are linked. Or that the whole effort would be
better served by a totally different approach. --Thanks, OBP


"John W. Vinson" wrote:

On Tue, 25 Aug 2009 10:59:01 -0700, oldblindpew
wrote:

This may prove to be an open-ended question, but here goes. I'm anticipating
having three tables with one-to-one relationships back to another table.

One to one relationships are VERY rare. See below.

All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

If the reality is that there is a "master" table and two "Child" tables, then
relate each child to the master. If the third table logically relates to data
in the second table, then cascade. It depends on the logical structure of the
data.


More info: The main table is Agreements. The sub-tables are Requirements,
Certificates, and Validations. Each Agreement imposes a set of Requirements.

But a one to one relationship implies that an Agreement can have zero or one
Requirement, never more. Are you perhaps using one *FIELD* per requirement? If
so you're not normalized.

A Certificate lists what is being offered to meet those Requirements, and a
Validation checks what is being offered against what is being required, field
by field.

Not record by record, using a one to many relationship?

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There is
truth in both statements as all of these are interrelated. I'm just afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out that
despite all your caution you made the wrong choice.

Just be sure you don't have repeating groups, to start with! Perhaps you could
post (real or hypothetical) sample data and indicate the field structures of
your tables.
--

John W. Vinson [MVP]

On Tue, 25 Aug 2009 15:18:11 -0700, oldblindpew
wrote:

Thanks for your reply. See also my response to Jerry Whittle.

This is about Certificates of Insurance furnished by subcontractors. Much
of my design is driven by the standard certificate form commonly seen in the
industry. This certificate form has lots of fields on it, and in order to
validate the certificate, each field has to be checked. My approach has been
to create one table for the certificate information and another similar table
to store the results of the validation, if ever I can get there.

To check or validate the certificate, there must be requirements to check
against. Originally I had a third table consisting of three records defining
three standard sets of insurance requirements, because we took sort of a
"Small, Medum, Large" approach to our requirements. Each Agreement pointed
to one of these three standard sets of requirements. But since it is
possible for any given agreement to modify or waive any given insurance
parameter, it seems better to let each agreement have its own unique set of
insurance requirements. Thus I arrive at three tables each relating back to
the Agreements table in a one-to-one fashion.

In order to ease the task of establishing the insurance requirements for
each agreement, I'll need to figure out how to enable the user to copy a
requirements record from one of the three standards, or from an existing
agreement, and then make whatever modifications may be called for by the
Agreement.

I appreciate your taking time to consider this and offer advice on whether
it matters how the tables are linked. Or that the whole effort would be
better served by a totally different approach. --Thanks, OBP

I think it WOULD be better served by a totally differnent approach - a
normalized Access database. g

It sounds very much to me like you have a very straightforward Many to Many
relationship between Certificates and Requirements. Each certificate has many
requirements; each requirement may occur on many Certificates.

You're solving the problem using spreadsheet logic: one field (column) for
each requirement. This is not ideal in Access! If your "Small" template has
(say) seventeen requirements, then you could have seventeen *RECORDS* in a
CertRequirements table, linked to this particular subcontractor's certificate,
and to a table of all the possible requirements that might arise (seventeen of
them from seventeen different records, in this instance). This would let you
add new requirements, waive individual requirements, add modifying notes or
comments to a requirement, etc. etc.

--

John W. Vinson [MVP]

You refused to respond back to my response so I am withdrawing from further
response to you!!!!

Steve


"oldblindpew" wrote in message
...
This may prove to be an open-ended question, but here goes. I'm
anticipating
having three tables with one-to-one relationships back to another table.
All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

More info: The main table is Agreements. The sub-tables are
Requirements,
Certificates, and Validations. Each Agreement imposes a set of
Requirements.
A Certificate lists what is being offered to meet those Requirements, and
a
Validation checks what is being offered against what is being required,
field
by field.

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There
is
truth in both statements as all of these are interrelated. I'm just
afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out
that
despite all your caution you made the wrong choice.

"Steve" schreef in bericht
...
You refused to respond back to my response so I am withdrawing from
further response to you!!!!

Steve


Calm down you idiot !!
Remember: No-one wants you here.... no-one needs you here...

But you are becoming famous nevertheless...
The stats for http://home.tiscali.nl/arracom/whoissteve.html are still
increasing daily...

Arno R

"Steve" wrote in message
...

Actually you don't have one-to-one relationships!

Don't you ever get tired of being wrong?

I'm sorry, but I don't know who you are or what responses your are referring
to.
--OBP

"Steve" wrote:

You refused to respond back to my response so I am withdrawing from further
response to you!!!!

Steve


"oldblindpew" wrote in message
...
This may prove to be an open-ended question, but here goes. I'm
anticipating
having three tables with one-to-one relationships back to another table.
All
of this information could therefore be placed in one massive table, but
somehow I feel it would be more manageable if separated. The question is,
should I key all three tables back to the main table, or should I key the
main to the first, the first to the second, and the second to the third?
Does it matter?

More info: The main table is Agreements. The sub-tables are
Requirements,
Certificates, and Validations. Each Agreement imposes a set of
Requirements.
A Certificate lists what is being offered to meet those Requirements, and
a
Validation checks what is being offered against what is being required,
field
by field.

So you could say Agreements result in Requirements, which result in
Certificates, which result in Validations. Or, you could say for each
Agreement there is a Requirement, a Certificate, and a Validation. There
is
truth in both statements as all of these are interrelated. I'm just
afraid
this will be another one of those cases where you have a choice, and it
doesn't really seem to matter, but one day long afterwards you find out
that
despite all your caution you made the wrong choice.