What is one-to-many relationship in DBMS, one-to-many relationship example, cardinality ratio one-to-many
If an entity [a record] of one entity set is associated with zero or more entities of the other entity set, then the cardinality ratio is said to be one-to-many from one side entity set to the many side entity set.
When we would say the relationship is one-to-many?
Assume two entity sets A and B. The relationship is one-to-many from A to B if and only if “an entity in A is associated with zero or more entities (records) in B and an entity in B is associated with only one entity (record) in A”.
If we put in simpler terms, entity set B is the many side for A and entity set A is the one side for B.
|Sample one-to-many relationship between entity sets|
- Each flight is having one or more attendants. [look from flight to flight_attendant]
- Each flight attendant is allotted with exactly one flight. [look from flight_attendant to flight]
|One-to-many relationship Has between entity sets Flight and Flight_Attendant|
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