Supertype on navicat data modeler how to#
Supertype on navicat data modeler series#

You can even create subtypes within subtypes – in fact, there is no hard limit in Ellie for the number of nested subtypes! What are the relationships between Subtype-supertype?Īll Ellie’s entities have their own Glossary entry, which you can access either via the Glossary menu itself or by double-clicking on an entity on the canvas. If something is common for all subtypes, you can handle it on the supertype (parent) level. This is a very powerful pattern that, while giving you a better understanding of the big picture, also makes your models visually simpler, as you don’t have to repeat relationships from every outside entity to every subtype entity.

(If you happen to wonder about the meaning of the various colors of the entities in this model, please refer to Modeler’s Corner #2!) This shows how we can define that User and Booking confirmation are things that link to all types of bookings, but Hotel for example is only linked to the relevant subtype. Having done that, our travel agency example might look like this:Īs you can see from the diagram above, the sub-entities can be neatly connected to “outside” entities at the same time as the parent entity is connected to others. Just click on an entity and drag it inside another, and they are glued together click and drag outside to un-glue. In Ellie, we use the box-within-a-box notation for subtypes.

Supertype on navicat data modeler how to#

How to Add a subtype entity in an Ellie model? This means that subtypes are always mandatory and mutually exclusive. Any single instance of the entity always represents a single subtype in our travel agency, an individual booking is always for either a flight or a hotel – not both at the same time, and you clearly can book a ‘nothing’. This is an example of a situation where we should reach into our toolbox for a subtype structure.Īn entity can have two or more subtypes. Still, both are very similar, essentially in that the user logs into our fancy system, selects their desired flight or hotel, and books them.

Clearly, there are two types of bookings: Flight booking and Hotel booking. With a single booking, you book a flight or a stay in a hotel. We have a system in which our users create Bookings. Let’s imagine we run a travel agency (not a great choice in 2021, but perhaps we are optimistic about the future!). These tools are repeatable patterns, and this time we’re going to cover a simple but yet very powerful one: entity subtypes. Now it’s time to think about using these blocks in the most efficient way.Ī good modeler has a toolbox from which they can draw various instruments when encountered with a suitable situation.

Supertype on navicat data modeler series#

A data model should show the relationships that exist between various customers, concepts, products, among many.The first three entries in our Modeler’s Corner series focused on getting your building blocks straight: identifying entities and utilizing Ellie’s entity categories to understand those entities better, and approaching the entities from the viewpoint of simple language: verbs and nouns. Data Modeling describes the creation of a visual representation (a chart or diagram) of a data system, or parts of that system. It is used to display and communicate connections between objects/concepts and shows their relationships.

The goal of a data model is to show what kind of data is being used and stored, the relationships between these entities (objects that exist), and ways the data can be organized. The more technologies being used, the more complex its data model. The different departments of an organization may be visualized as the links of a chain, with some links (departments) using different technologies. According to Pascal Desmarets, Founder and CEO of Hackolade: As a result, not all the links in this chain are altered with a single command, and not at the same time. “The ability to handle complexity and scale is another challenge. Their schemas are flying around, each of them having its own lifecycle.” It seems that companies are having hundreds, sometimes thousands, if not tens of thousands, of APIs and microservices, and these are handled using dozens of different technologies. With the creation and collection of data continuously growing, extracting insights from the overabundance of data available needs well-designed data models. Developing a good data model requires an understanding of the organization’s processes, customers, and services/products, as well as the ability to organize those processes, etc., in a visual format.