The ORM Foundation

This is the Relational View corresponding to the model in the previous message, produced by the test version of NORMA for VS 2017.

Linking an Enrollment to a LabSessionNr doesn't seem correct to me (several lab sessions may have the same number). I would have linked it to LabSession. I have added an external inclusion constraint to your model, which, I believe, is equivalent to yours. The resulting RM does not enforce such external constraints. I attach the figures in ...

Thanks for looking into this (btw, Nicola is a male Italian name). Please let me know if you would like me to set up an account for you in our JIRA system. Thanks, I can set up one through the Sign Up page if necessary. I get a different relational mapping result when I use NORMA. I am using the current test of NORMA for VS 2017. ...

I am not sure that I have found new bugs. Rather, a missing feature. Anyway, I plan to experiment with NORMA a bit more and study the details of the mapping algorithm as described in ORM's books. Then I'll report back here or in the issue tracker, as deemed appropriate.

With respect to (3), You claimed that my model contains redundant fact types so please could you tell me which of the fact types in my model you think are "redundant"? It's the ones highlighted in the picture. If you keep them, you must add external equality constraints (e.g., if some Student has a GPA and that Student applies to ...

Generated relational view attached. This model has so many problems that I don't know where to start with. It can be succintly summarised in two words as: “no integrity”. Again, AFAICS, this is because integrity constraints in the ORM model are not used by the translation algorithm. Note that it is possible to build a Relational model that ...

The issue becomes more apparent as soon as the model becomes more complex. Example from previous thread: 

Generated Relational view attached. Do you see the problem? The external constraint on {Course, Student} is not enforced. This is simply a matter of setting the PK of StudentSubscribesToLabSession to {courseCode, studentId}. So, in general NORMA seems to ignore most external constraints. 

 Simple example to start with:  

The point about "ORM being better than anything else"  is in part related to the fact that NORMA uses RMAP to instantly create a 5NF logical model I can certainly appreciate that ORM is more formal and more expressive than ER, and has great tooling support (otherwise, I wouldn't be in this forum). But the fact that it can ...