One of my clients has been experimenting with their first Conceptual Data Model in PowerDesigner. They created the model using the PowerDesigner client software, and checked it in to the repository.
The PowerDesigner Web allows anyone with the right privileges to view your models using a web browser – here’s part of a Conceptual Data Model, shown in PowerDesigner Web:
You can see that I’ve selected one of the Relationships (called “Supplier >- provide -< Ingredient”) – the Relationship name is visible on the diagram, along with the two role names (“provide” and “be available from”).
My client was curious, because the same relationship, when displayed in the PowerDesigner client, did not show the Relationship name, only the role names. He wondered why that was so, and what he could do about it.
If you have the same question, or you are just as curious, please watch this video.
By the way, the diagrams shown here are based on those in Steve Hoberman’s latest book, The Rosedata Stone.
I’m keeping the numbers low for this session, partly to keep it informal, and partly due to platform limitations. I’m pleased to say that it’s now fully booked. I’m sure I’ll repeat it sometime in the near future.
PowerDesigner Web has been around for some time now, exposing the content of the PowerDesigner repository to a wider audience and giving users the ability to create and edit some types of model. With the introduction of PowerDesigner 16.7, the types of model that can be created and edited has grown, and has started to get George interested.
In this session, George will take you through the background to PD Web and show you some of the interesting features he’s found, focusing mainly on the things you can do in PD Web that you can’t do in the PowerDesigner client application:
Reverse-engineering JSON documents and Schemas
Productivity aids when editing Conceptual and Physical Data Models
Structured data types in the Conceptual Data Model
Exporting a diagram to PowerPoint as symbols that can be individually edited
It overran quite a lot today, but most people attending didn’t seem to mind. I’m talking about Jurgen Ziemer’s presentation for DAMA South Africa, talking about the FIB-DM data model he’s built from the FIBO ontology – you can see his presentation here. It’s a very large model, some of which is available for free – click on the Download link at https://fib-dm.com/ to ask for the free version.
The FIB-DM makes a lot of use of inheritance hierarchies, with some multiple inheritance in there as well, so it can take a while to get to grips with the model.
For example, I might be interested in knowing how the model handles Deposit Accounts. If I right-click the entity name in the object browser, I can use the context menu to find the diagram that contains the Deposit Account entity – it’s called “FIBO Finance, Business and Commerce – Products and Services, Clients and Accounts”, and it’s three levels down inside the package hierarchy within the model. Here’s what that diagram looks like – I’ve highlighted the Deposit Account entity:
I can see that the entity is in one of those inheritance hierarchies, and that it’s got relationships to a couple of child entities. What I can’t see here are any connections to other objects that the modeller decided NOT to include on this diagram. That could be another parent or child entity, traceability links, or other relationships. What I’d like to see is a diagram that shows me the complete context for that entity – everything in the ‘proximity’ of the entity.
I could carefully work through the dependencies the entity has, and then select them for inclusion in a diagram, but I’d like a quicker way of doing it.
That’s where the CDM LDM Productivity model extension comes in – it can create that ‘Proximity’ diagram for me with a single click (I can also refresh it with a single click to make sure it’s up to date). Here it is:
There isn’t much there that isn’t on the other diagram, just an extra parent entity – Banking Product. Crikey, that changes my understanding a little bit, I didn’t know about that, and I’d like to find out more. To start with, I’d like to see the inheritance hierarchies in more detail. This is also provided by the CDM LDM Productivity model extension – with one click I can create an Inheritance diagram for the entity, which can also be refreshed whenever I want:
I’ve hidden all the child entities from the diagram, as I’m primarily interested in the entity’s parentage – I can see that the entity is a great-grandchild of Product, and also a great-grandchild of Account.
These are just two of the features provided by the CDM LDM Productivity model extension – it also includes configurable naming standards, diagram completeness, and other features to improve the productivity of anyone working with Conceptual or Logical Data Models in PowerDesigner.
This was one of my first blog posts and has always proved popular, so I’ve brought it up to date.
I remember the first time I came across SAP PowerDesigner. It was version 11, re-badged by Quest Software as QDesigner. This was before Quest started selling their own modelling tool.
I had multiple ERDs in my Conceptual Data Model, and I wanted to include existing relationships on a new ERD I was putting together. I was used to a command in Oracle Designer that would add all missing relationships (including inheritances) to the diagram – every existing relationship that connects two entities that already appear on the diagram would be included.
After a search, I found the equivalent command in PowerDesigner (there’s a ‘complete links’ tool on the Diagram toolbar – see below).
However, I often just wanted to include one or two particular relationships on the diagram, so I tried dragging them onto the diagram from the browser. I was really annoyed at the result, and took a while to understand what was going on. I don’t think it’s a problem with PowerDesigner really, but a symptom of the fact that it doesn’t always work in the same way as other tools.
The confusion was later evidenced by a thread on the old Info Advisors PowerDesigner group – “Even when dragging a relationship / reference from the browser into a diagram where the participating entities have already been included as symbols, PD creates new symbols for them, rather than connect the relationship’s symbol to the existing entities’ symbols. One has to manually delete the extra ones; a nuisance...”.
When you drag a relationship onto a diagram from the browser, PowerDesigner will automatically include the two entity symbols as well, even if the entities already appear on the diagram. These new entity symbols are called graphical synonyms, and can actually be very useful. If you do create unwanted graphical synonyms, all you need to do is delete the new entity symbols, and the relationship symbol will snap to the original entity symbols. This could be a real pain in the neck to do if you drag a lot of relationships at the same time.
Here’s how to prevent this happening
Prevention is better than cure, so remember this simple trick
hold down the <Shift> key when you drag the relationship(s) from the browser to the diagram – the relationship will be drawn between the existing entity symbols and no new graphical synonyms will be added.
One problem with dragging relationships from the browser is ‘How do I know which relationship is which?‘ Here’s the list of relationships in one of the supplied demo models:
How well do you know your model? In this model, the relationship names are short, and we have some duplicate names as well. If you want to, you can make it more difficult to create duplicate names, using the ‘unique code’ setting in the model options. As long as you synchronise your relationship names and codes, you won’t get duplicates.
In anything but the simplest model, or one you know exceptionally well, that still won’t help you know which relationship you need to drag onto your diagram. The names are just too short.
In this model, the two ‘Belongs to’ relationships could be referred to as “EmployeeBelongs toDivision” and “TaskBelongs toProject“. Now, you could change the relationship names to include one or both of the entity names which would certainly make the browser list easier to use:
That gives you a re-work overhead you don’t really want – if (sorry, when) you need to move a relationship end from one entity to another, you’ll have to remember to rename the relationship. By the way, don’t worry about displaying the extra-long name on diagrams, because you can choose to display one or both role names instead of the relationship name (you DO use role names don’t you?), like this:
I suggest you come up with a standard for relationship names so you can make sense of the browser – meaningful relationship names may also be useful in reports.
Alternatively, you could customise PowerDesigner by adding an Event Handler or a custom model check to derive relationship names, such as “Division Employs Employee” or “Project Requires Task”. If you do create such an Event Handler, remember to check for duplicate names.
I’ve actually done this so you don’t have to – the CDM LDM Productivity model extension applies a naming standard based on the entity names, one of the role names, and the relationship type.
Is there a better way to choose what to include?
If I want to include missing relationships in an ERD, there are better ways. If I want to see a list of my relationships, there’s a better way of doing that as well – look further down this blog post for that one.
OK, let’s get back to adding missing relationships. Here’s the first easy way – select the Show / Hide Symbols command on the Symbol menu, and choose the relationships you want to include:
Notice that one of the relationships is listed as ‘Hidden’. It was previously displayed on the ERD, but I decided to hide it. I’ve selected it for inclusion, and it will re-appear in the diagram in the same position and style as it appeared before (assuming the entity symbols haven’t moved, of course). Including missing relationships this way will not result in graphical synonyms being added (unless, perhaps – I haven’t tested this – they were previously attached to graphical synonyms that are still present).
Notice also that one relationship is listed as ‘None’, meaning that the symbol just isn’t known to the diagram, hidden or otherwise. perhaps it used to be there and I chose to delete the symbol.
Don’t worry if your Show / Hide Symbols dialogue doesn’t look like the one above. I tailored mine using the customisation tool , so you can replicate yourself.
The second easy way to add missing relationships is the “Add missing link” tool on the Diagram Toolbar. If you have nothing selected, this will add every link symbol that is missing from the diagram, which may give you a few surprises. If you want to include all relationships for, say, the entity Team, here’s what you do:
select the symbol for the “Team” entity
click on the “Add missing link” tool
PowerDesigner presents a choice for you:
select the first options to add all missing links for the selected entity. This will include relationships and traceability links connecting the entity other symbols that er already on the diagram.
Now for my final point, listing relationships without using the browser. Which would you rather work with, the list of names in the browser, or a list that you have control over? In the list of relationships shown below (via Relationships on the Model menu), I can choose the properties I want to see, the order in which to show them, sort the listing, and filter according to property contents:
Again, this is a customised list, so it may take you a few minutes to achieve, but the results will stay with you – I carried out this customisation several months ago. I can click on the column headings to sort the list if I want to. I can also edit any of the properties that are displayed, as long as they aren’t shown in grey. By adding new rows to the list, I can create new relationships, which will automatically be added to my current diagram.
By the way, the ‘S’ column tells me whether or not the relationship has a symbol on a diagram – the first one on the list does not have a symbol.
If you want to include this list in reports, or take snapshots of the content from time to time, you can re-create it in a List Report.
There is another way
The CDM LDM Productivity model extension includes a ‘completeness’ feature, which allows you to select an entity on the diagram or in the browser, and then choose the relationships you want to include (as well as inheritance hierarchies and traceability links).