Database: relationship degree and cardinality

The degree of a relationship is different from the degree of a relation (table). Both definitions are likely to get mixed up and cause confusion.

  1. Relation in this context (in relational databases) is synonym to a “table” Whereas,
  2. Relationship is synonym to “a connection between tables (relations)”.

We have to consider both of these characteristics known as “degree” and “cardinality” of

  1. relations (tables) and
  2. relationships


1. in a relation (table)

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i) Degree – Number of fields (columns) in relation.

ii) Cardinality – number of records (rows) in relation.

2. in a relationship

i) Degree – Number of entities (tables) involved in a relationship (Unary, Binary, Ternary, N-array)

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ii) Cardinality – Number of connections that each record (row/data) of an entity might establish with the records of another entity. (One to one, One to many, many to many)

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