A new syntax for Entity-Relationship (or Information Enineering) ERD diagrams

0 votes
asked Mar 19 in Closed feature request by nicamlg (140 points)

I would like to point there's already some kind of "textual representation" for ER that could have been ported to PlantUML. I have found a comprehensive document about it. In short, it could have been like this:


' __ could signal the Primary Key (just a suggestion)

entity Bus (__reg_no, make, size, deck, no_of_pass)
entity Route (__route_no, avg_pass)
entity Driver (__emp_no, name, cell)
entity Stage (__stage_no)
entity Town (__name)

Bus   m..1 Route : is serviced by
Route 1..m Stage : comprises
Driver m..1  : is allocated to
Stage n..m Town : Passes-though
Route n..m Town : Passes-though



Which is more readable than the cryptic }|-|| (which is related to the drawn symbols, I know).
Also, the attributes can be written in a more classical way, less "java-ish", as shown in the entities declarations. I.e., the "Bus" entity would be shown as:

If attributes are listed and not hidden (`hide attributes`, i.e.) they could be also drawn following the ERD stadard, UseCase-like oval surrounding their entity, something like this:

NOTE: Since I used a Use-case diagram, I couldn't add the ERD symbols to the line ends.

And, just for completeness and drive the developers crazy, declare the relationships as diamonds if declared:

skinparam erdModel chen


But, just a thought. Document the current implementation would be nice enough. O:)

[NOTE 2: I admit I do not usually add the attributes in E-R diagrams...]

commented Mar 19 by zimchaa (980 points)
It may be possible to recreate this type of approach using the Macros, and some examples already exist for the more descriptive relationships - examples include the C4 PlantUML library https://github.com/RicardoNiepel/C4-PlantUML with a simple approach (using Rel keyword) but there are more complex examples, https://github.com/ebbypeter/Archimate-PlantUML - using Rel_RelationType keywords -

"The RelationTypes supported are:

commented Apr 11 by nicamlg (140 points)
The question is that, AFAIK, using macros means that "standard"

  Bus   m..1 Route : is serviced by

Would become something like:

  er_relationship ('Bus',  'm..1', 'Route' , 'is serviced by')

The attribute drawing would not be a problem, I think (unless macros need a fixed number of parameters...), because the syntax is already similar (I suppose this is what led you to suggest it :-)).

But, aliasing ' }|-|{ ' to 'm..m' etc., would increase the readability of the diagram source code.
commented Aug 23 by nicamlg (140 points)
Any new on this?

That way we could have a true ERD instead of a version of the class UML diagram.

An example of ERD, and how could be accomplished with PlantUML, since all the elements exist already.


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