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  • Re: How to add Exclusion Constraint in VisioModeler?

    Hi Charles My tutorial on how to use VisioModeler can be downloaded from http://www.orm.net/pdf/VMuse.pdf Here is an excerpt from that tutorial on adding exclusion constraints (but you already figured it out!)To apply an exclusion constraint over two or more compatible role sequences, click the exclusion constraint button, then hold the shift ...
    Posted to Other Tools (Forum) by Terry Halpin on Wed, Oct 29 2008
  • Re: Boleans - unary vs binary fact types

    Hi Rolemo Unaries (e.g. Person smokes) are often more natural than their equivalent binaries (e.g. Person has SmokingStatus), so I tend to use them a lot. However if you have a set of 2 or more mutually exclusive unaries (e.g. Person is male; Person is female) it is more efficient to use a single binary (e.g. Person is of Gender {&#39;M&#39;, ...
    Posted to User experience (Forum) by Terry Halpin on Mon, Oct 27 2008
  • Re: Derivation and tables

    Hi Orion Thanks for answering Rolemo&#39;s question. As a minor refinement to your answer, ORM 2 allows&nbsp;subtypes to be (simply)&nbsp;asserted, derived, or semiderived. So&nbsp;it is OK to simply assert the subtypes you show without a definition, if that is what you prefer. We hope soon to distinguish these 3 kinds of subtypes graphically as ...
    Posted to User experience (Forum) by Terry Halpin on Mon, Oct 27 2008
  • Re: independent objectified fact type

    Hi Rolemo If Hat and Man play no other roles in the global schema then Yes: because they have not been declared independent, the disjunction of their fact roles (in this case just one role for each) is mandatory. In a typical schema however, Man would play many more roles, so the single role of having a hat would not then be implied ...
    Posted to User experience (Forum) by Terry Halpin on Fri, Oct 24 2008
  • Re: using NORMA reports

    Rolemo The check boxes in model reports are for the client to indicate whether they agree&nbsp;that the constraint applies to their business domain.&nbsp;There is also a field at the bottom for them to sign off on the report.&nbsp;We plan to add a date field and many further improvements. Cheers Terry
    Posted to User experience (Forum) by Terry Halpin on Fri, Oct 24 2008
  • Re: independent objectified fact type

    Hi Rolemo In a typical business model, many roles are optional rather than being mandatory (e.g. It is typically mandatory for customers to have a name but optional for them to have a fax number). It is rare to have a simple object type independent, although fairly common to have an objectified association&nbsp;independent. The two constructs are ...
    Posted to User experience (Forum) by Terry Halpin on Fri, Oct 24 2008
  • Re: independent objectified fact type

    Rolemo For uniformity, we decided to make the rules for objectified associations the same as for normal object types (by default, an object type is not independent). Suppose you had a schema consisting of just the fact type &quot;Person(.id) was born in Country(.code)&quot;. &nbsp;By default, Person and country are not independent, so their roles ...
    Posted to User experience (Forum) by Terry Halpin on Thu, Oct 23 2008
  • Re: values as subsets

    Rolemo It sounds like you have a mandatory, n:1&nbsp;fact type &quot;Employee(.id) has PermissionLevel(.name)&quot; with the value constraint {&#39;Organization&#39;, &#39;Region&#39;, &#39;Country&#39;} on PermissionLevel. Adding subsetting doesn&#39;t help. You need to specify elsewhere what semantics you attach to these levels. Depending on ...
    Posted to User experience (Forum) by Terry Halpin on Wed, Oct 22 2008
  • Re: Derivation vs. Subset Constraint

    Rolemo For this example, I would choose to make the fact type &quot;Project is completed&quot; as simply derived. The subset constraint approach would create an extra Boolean column &quot;isCompleted&quot; which would then have to be kept in sync with the completionDate column (isCompleted set to true/false if completionDate is not-null/null). It ...
    Posted to User experience (Forum) by Terry Halpin on Tue, Oct 21 2008
  • Re: how to define a supertype as secondary

    Apparently you are using an old version of Lab 4. We changed the way subtyping works so that now a solid arrow is always used if that path provides a way to the preferred identifier. I just sent Ken the latest version of Lab 4&nbsp;which he should place soon in the library. This shows solid arrows, as you are experiencing. Cheers Terry
    Posted to User experience (Forum) by Terry Halpin on Tue, Oct 21 2008
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