CODEWITHSUNDEEP
database-designschemarelational-databaseerd
Dave Clarke
Dave Clarke

Reputation: 2696

Multi-valued attributes in a relational database

What is the best method of implementing multi-valued attributes in a relational database?

I'm trying to convert an ER diagram into a relational schema, and I have this problem:

I have a table of 'Programmes' with attributes such as Programme ID, type, title, description etc - but then also have Actors - obviously this is multi-valued as a specific programme will have multiple actors in.

How should I represent this?

Upvotes: 0

Views: 3044

Answers (2)

djb
djb

Reputation: 185

If an actor can have Many programmes and a programme can have Many actors this sounds like a classic Many-to-Many relationship. Create a third table called programme_actors or perhaps cast with two columns: the primary keys of each of the two joined tables.

Upvotes: 2

Drunix
Drunix

Reputation: 3343

If an actor also may appear in several programmes, use a join table with foreign keys on both programme and actor and possibly other attributes like role.

Upvotes: 1

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