CODEWITHSUNDEEP
erdentity-relationship
Amit
Amit

Reputation: 6304

Entity Relationship Diagram - ISA direction

In ERD I am used to see something like:

enter image description here

But I ran into some cases where the triangle is upsidedown, like:

enter image description here

So I wondered, does the direction of the ISA triangle matters? It seems only logical that the pointy vertex would point at the parent, and inheritants would go from the edge itself.

Upvotes: 0

Views: 2595

Answers (1)

reaanb
reaanb

Reputation: 10064

There's no inherent meaning in the orientation of the triangle. In your examples, they mean exactly the same thing. Different tools might implement it differently, and there are other conventions for subtyping besides triangles.

I suggest you pick the more popular convention and stick with it.

Upvotes: 1

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