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Data & Analytics · Intermediate

Crow's Foot Notation

An ERD notation that uses symbols at line ends to show cardinality: a three-pronged 'crow's foot' for many, a bar for one and a circle for zero.

Definition

Each relationship end shows a minimum and a maximum. A circle plus a crow's foot means zero or many, two bars mean exactly one, and a bar plus a crow's foot means one or many. It is the most widely used ERD notation in industry tools.

Exam tip

The inner symbol (closest to the entity) is the maximum and the outer symbol is the minimum; read both.

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