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relationshiperd
Tom Lever
Tom Lever

Reputation: 445

Drawing Relationships In Entity Relationship Diagram

I used Azure to create a database. I used Azure Data Studio and https://github.com/R0tenur/visualization to create the following Entity Relationship Diagram / Relational Model (?). Are the relationships drawn correctly or reversed? Is it correct to read one relationship as "Between one and one course has between one and many outcomes."?

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Upvotes: 1

Views: 180

Answers (1)

Christophe
Christophe

Reputation: 73530

The relationships seem indeed inverted: this diagram tells that:

  • an outcome shall have one or many courses
  • each course must have one outcome

The cardinality symbol on the side of the outcomes tells how many outcomes can be related to one element of the opposite side, and vice-versa. The element closest to a table can be a bar (one) or a trident (many). The element next to it tells about the participation, which is either a bar (mandatory) or a circle (optional).

The foreign keys in your tables confirm that the other relationships are also inverted.

Here a link with more explanations on the crow's foot ERD notation and of course wikipedia.

Upvotes: 1

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