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ER: All Cardinality Types

Every crow's-foot cardinality combination side by side — the reference chart for reading any combination at a glance instead of checking each relationship's own page.

er-all-cardinality-types.mmd
erDiagram
  A ||--|| B : "one-to-one"
  C ||--o{ D : "one-to-many"
  E |o--|{ F : opt-to-many
  G }|--o{ H : "many-to-many"
Output
ER diagram, Zombie Mermaid A (no attributes) B (no attributes) C (no attributes) D (no attributes) E (no attributes) F (no attributes) G (no attributes) H (no attributes) one-to-one one-to-many opt-to-many many-to-many

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