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Sahithyan's S3
1
Sahithyan's S3 — Database Systems

Crows Foot Notation

One of the ER diagram notations.

Entity

Section titled “Entity”

Entity name is singluar. Represented by a rectangle.

Attribute

Section titled “Attribute”

Included inside the entity rectangle.

Key attribute

Section titled “Key attribute”

Prefixed with an ”*”.

Relationship

Section titled “Relationship”

Represented by a line. Can have 2 indicators on each ends.

  • Multiplicity
  • Optional/not

Multiplicity

Section titled “Multiplicity”

Refers to maximum number of times that an instance of an entity can be associated with instances in the related entity. Indicated close to the entity rectangle. Indicated by:

  • | means 1
  • > means many

Optionality

Section titled “Optionality”

Refers to the minimum number of times that an instance can be related to others. Indicated next to the multiplicity indicator. Indicated by:

  • | means 1
  • o means 0