techniques:erd

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Crows Feet diagrams are used by System Architect and other ERD tool sets to show the cardinality and the type of relationship between two entities.

Crows Feet Diagram Meanings

Line endings give the cardinality

Line EndingMeaning
has a cardinality of 0 or more
has a cardinality of 1 or more
has a cardinality of 0 or 1
has a cardinality of exactly one
n to n1..n2 has a cardinality of n to n1 to n2

Line types give the nature of the relationship.

Line TypeMeaning
is an identifying relationship
is a non-identifying relationship
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