General Discussion

ORM and ERM Difference

vikaskale — 2007-10-27T09:16:26Z

Hello everyone,

I am learning Data modelling and want to know

1.the difference between the ORM and ERM.
2. significance of ORM

Thanks and Regards
Vikas Kale

Bug when removing ValueTypes from ORM diagram?

Scot — 2006-06-29T17:05:12Z

As a postscript to this irritating bug:

If you delete the predicate first, then delete the object type, answering "no" both times, it behaves as expected.

FYI,
Scot.

Entity with Values attached to multiple Entities...

Scot — 2005-12-01T12:29:19Z

MartinPlatt wrote

Guys,

would there be any way of creating an entity with values to represent say, some standard columns that might be found in all tables in a solution.

I thought that it might be useful to have some entity that plays no functional role, to be attached to all entites, and thus represent say audit columns, or some such, in all entities? Can that be done?

Search for my discussion on co-referencing for more details, but I suspect that is what you did below. It will sort of work, as you are kinda defining a composite object type. The problem is that co-referencing is intended to handle complex reference schemes, not complex type definitions. As such, this approach is a neat shortcut until you get around to wanting to design and implement the actual database at which time it can cause problems.

For example, sometimes, you have constraints across the component of the complex type and other fact types.

I think that that can be done, but I'm not sure if my approach is correct, so that why I asked. Next, it appears, when I generate ERDs If for example I have an entity VersColumns, and a value of Vers, the generated name is VerColumnVers - is there any way of forcing that entity to be resolved as just Vers in the resulting ERDs. I know that I can go into each column, and change the physical name, but for some reason, I get the conceptual name as Vers, but the physical name as VersColumnVers.

The names generated when co-referencing are not ideal and usually require changing the names on the physical model.

Scot.

Splitting ORM diagrams??

Scot — 2005-12-01T12:24:02Z

MartinPlatt wrote

Is there any point in splitting ORM diagrams?

Would splitting make ERD generation quicker, or would it just complicate things?

At the moment I'm considering whether it would be worthwhile to split associated entities into their own files, but I don't want to do that until I've heard if it's worthwhile!

I don't know about performance, I suspect having multiple source models to one database model diagram would, if anything, slow down generation (as well as introduce all sorts of problems when source models share a given object type/fact type, use of abbreviations, keeping name changes, etc.).

The intention behind source models was to allow for multiple modelers to work on a project. The reality is that it wasn't implemented well and, in my opinion, is best avoided.

Scot.

Large ORM project and updating source models...

MartinPlatt — 2005-11-27T22:08:24Z

Scot

Large ORM project - segmenting onto pages?

MartinPlatt — 2005-11-20T21:22:55Z

Scot,

Thanks once again for the feedback. I think that the layout is important to the readability of the diagrams, don't you? I've also found that the diagrams seem to grow organically, particularly if you're working on agile projects. ORM lends itself really nicely to design treaking in this way, but the diagrams in VEA don't, because if you cut and paste the diagram, you get another object.

What I have been doing in general is having the central entity in the middle of the page, it's entites and values to the right, and its parent entities to the left. In general, that seems to work quite nicely, I was just interested in how others lay out their diagrams; thank you for letting me know how you do yours!

I'm also looking for ways to introduce a prescriptive way to use ORM in a project, to document that process for any teams to use.

Cheers,

Martin.

Making Visio ORM Diagram readable as conceptual diagram.

MartinPlatt — 2005-11-20T21:16:46Z

Scot,

I see what you're saying, but think that there should be the ability to 'scope' and trim back irrelevant functionality, using something similar to the system boundary.

I found that treaking the document settings does help somewhat - I tend to take down requirements and work through their details, then commit the ORM details to a document. I guess that process would remove some of the relevance to clients. I would expect to be able to take a logical design, and push that through to physical design at the very least, by changing 'views' on the same information. This process can be partly done, but it would be good to take that further and use it as a toll that can be used for the whole process rather than always having to resort to paper, as is the case with most tools.

My view is that these tools should be improved to make then truly useful, I'm sure that this can be done because the process is almost there already, but does not go all the way?

Cheers,

Martin.

the question is moved to ORM2 proposal

g_vanine — 2005-06-24T20:13:22Z

I removed this question

to change default zoom

g_vanine — 2005-06-24T15:04:28Z

When I open VEA diagram, it is always zoomed to 67%.
How can I change it (to, e.g., 125% for all openings)?

lost

g_vanine — 2005-06-20T10:28:01Z

1)
In VM3.1 I can navigate to any model fragment (even external, i.e. in another file), by double-clicking on an element (call it type) in Object Types window.
Is there any (easy) alternative to navigate through model in VEA?

2)
In VM3.1 I can conrol (edit, resize, change position and text of names) graphic representation of model elements and in VEA? No way?

3)
I cannot find How can I visualize role names in VEA (from Database Properties | Readings |Role name)?
BTW, are the role names some kind of synonym/alternative to predicates?

4)
I am seriously thinking to shift all ORM Source model elaboration to VM3.1 (with further export/import to VEA) for further development. The VM3.1 is more intuitive, comfortable, easy, doesn't need VS .NET installed and so can be easily shared/presented to domain specialists.
I'd like to hear any comments against this

values vs entity types

g_vanine — 2005-06-19T15:05:30Z

This
http://www.objectrolemodeling.com/Discussions/tabid/27/forumid/3/threadid/354/scope/posts/Default.aspx
is also about

example of dynamic constraint?

g_vanine — 2005-06-19T09:51:38Z

It seems I lost time in vain since I ordered first edition [1] (really 3d one of [3]?)
[1]
Terry Halpin
Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design
ISBN: 1558606726
Publisher: Morgan Kaufmann; 1st edition (April 6, 2001)
792 pages,
[2]
Terry Halpin
Conceptual Schema and Relational Database Design
Publisher: Prentice Hall; 2nd ed edition (May 1, 1995)
ISBN: 0133557022
547 pages
[3]
Nijssen, G. M. and T. A. Halpin. 1989.
Conceptual Schema and Relational Database Design: A Fact Oriented Approach.
xiv + 342pp.
Prentice Hall of Australia Pty Ltd. Sydney.
ISBN 0-13-167263-0

no need of reference schemes in ORM Source Model?

Scot — 2005-06-15T14:02:59Z

We seem to be talking about different things. See my other post where I defined "reference mode/scheme". I'm not talking about re-using model components and how you reference within VEA such that it knows you are using some component in another file. I'm talking about identifying real world things and modeling them (regardless of how you do it in some tool for use in more than one application). Very different.

Scot.

ORM Source Model vs ORM Diagram?

g_vanine — 2005-06-14T01:18:27Z

The problem is that I managed to insert model graphic elements without any underlying semantics into ORM Source model and intermix them. And only after that I understood that Visio is drawing tool with some added above add-ins/moules for modeling.

I ordered Terry's book 2 weeks ago in local bookshop and the waiting time estimate was given from 6 weeks on (I do not have other possibilities to get to it)

interop with Visio 2000 Pro

g_vanine — 2005-06-14T00:56:09Z

I do not need to work, just to show (a copy) in some way to client that has Visio 2000 Pro.

VisioModeler 3.1, Orthogonal Toolbox interop

Scot — 2005-06-14T00:48:38Z

You can't import from VEA into VM. VM is a legacy product that pre-dates VEA.

Visio 2000's version of the ORM solution did not display most constraints. You have VEA 2002, so you can disregard that statement.

The toolbox doesn't work with VM. VM does have an API, so if you wanted to write your own code against it, you could.

Scot.

Ref Mode Types: references or really just properties?

Scot — 2005-06-14T00:44:28Z

The reference mode "type" setting is for documentation only and has no effect on any aspect of code generation. You are right, it is probably not a conceptual issue. Terry defines each type in his book if you want to know what they mean, but honestly, I never use it and you can ignore it.

The plus symbol is used in some writings to indicate that numeric operations (additional, subtraction, etc.) can be performed on the data.

Terry likes to model date as an entity type with formatting as the reference mode (Date(ymd) ), I like to model it as a value type (Date() ). Both work fine. I agree, and to me, formatting is not really a reference mode.

Again, I think you are getting bogged down in technicalities. You might want to step back and really use the tool for a while before you worry about some of this stuff.

Scot.

'Creating Conceptual Source Components' by P.Hallock

g_vanine — 2005-06-13T19:41:04Z

Almost all my posts revolve around the same problem:
- how to reference conceptual components, concepts for their reuse in ORM?
- whether "simple/internal ref scheme" (aka "label") of entity is conceptual?

It seems that ORM's reference (scheme)/identifier is not conceptual but database and specifically RDBMS notion [1], and even not identifying but only categorizing (i.e. identifying between various formats, units of the same entity instance and not between various instances of entity) notion.
In other words, ORM should not have used implementation-biased (I'd say deployment, after-decision issues) notions in conceptual models. What if I am going to use XML-files storage, or even do not persist data, etc.? It is what ADO.NET is all about

And how would someone construct components reutilization (how to reference different definitions of the same component/concept) in ORM and VEA, or even just different conceptual entities?

I just want to repeat that I had not come out of ORM Source Model and would like to understand it before making decision that I am going to use RDBMS, and therefore VEA's Database/ER Source Model. I really think about to pass to further modeling in UML

Once again, information (or even data) modeling does not mean modeling data persistence and does not mean data persistence specifically through necessarily implementation of RDBMS

Even, if to consider that data modeling is modeling of persistence and through RDBMS, then it is still unclear how to realize conceptual components reuse, i.e. referencing, in ORM or in VEA.

[1]
G. Vanine.
Ref Mode Types: references - are they identities or just database (implemetation-biased) properties?
The question posted in this forum.
http://www.objectrolemodeling.com/Discussions/tabid/27/forumid/7/threadid/336/scope/posts/Default.aspx

on models&fragments combining ('just how the developers of VEA intended source models to be used')

g_vanine — 2005-06-12T17:14:43Z

I propose to use the term component or concept for this "model in one file", and (conceptual) model as consisting of concepts and/or (conceptual) components and ohter models (even from various applications).

aloud (ORM and A&D practical approaches/attitudes/techniques/classification/notation)

g_vanine — 2005-06-11T12:42:15Z

I found that
http://www.casetalk.com/php/index.php?Article20030603

coincide exactly with my mode of thinking, experience, terms and classification

My employer just demanded and just tomorrow to complete analysis by creating and fixing it in isolatedContacts and Organizations entities.

He repeated:
"This is vey simple - no need for relationships and we need to fix analysis in diagram and return to model ("contacts management" in his terminology) after completing another project."

Notwithstanding on what I was saying I've heard: "tomorrow", "simple", "isolated entities" of jsut Contacts and Organizations but counting for various floating meanings of roles, addresses, relationships, contact mechanisms, departments, persons, group of enterpises, etc., i.e. all from "Person and Organizations" model.

Just very simple: Organizations and Contacts (but with multiple meanings) but counting for all

There were 2 great misunderstanding:

To employer Analysis is diagrams and to me just words (use cases, current and target "what" of systems, user requirements).

For me, discrimination of "isolated" entities is possible as a result of completion of the Design, i.e. of complete logical model (with all relationships/associations).
Otherwise, they are 0NF (0th-Normal Form) calculation spreadsheets, with hundreds of columns.

It is not even more complicated to create (than a model) but it is also does not make any sense (self-contradictory task).

This eventually led me to great losses of time and stress. I promised to complete it tomorrow and then each time again and again re-understood that it just doesn't make any sense.

I unilaterally broke dependent work (employment contract) and declared that I finish doing it as free-lancer.

To my employer, and now, I hope, a client, it is still a big bewilderment. What was the problem in creating isolated Contacts (with various meanings, as events, as persons, changeable in time and depending on roles, raltionships, etc.) and Organizations counting for all, completing another project and returning to creation of model.

But the problem was that I really was greatly confused on terminology used and couldn't stay firm from the start

General Discussion

ORM and ERM Difference

Bug when removing ValueTypes from ORM diagram?

Entity with Values attached to multiple Entities...

Splitting ORM diagrams??

Large ORM project and updating source models...

Large ORM project - segmenting onto pages?

Making Visio ORM Diagram readable as conceptual diagram.

the question is moved to ORM2 proposal

to change default zoom

lost

values vs entity types

example of dynamic constraint?

no need of reference schemes in ORM Source Model?

ORM Source Model vs ORM Diagram?

interop with Visio 2000 Pro

VisioModeler 3.1, Orthogonal Toolbox interop

Ref Mode Types: references or really just properties?

'Creating Conceptual Source Components' by P.Hallock

on models&fragments combining ('just how the developers of VEA intended source models to be used')

aloud (ORM and A&D practical approaches/attitudes/techniques/classification/notation)

More...