CODEWITHSUNDEEP
sql-server
NoviceToDotNet
NoviceToDotNet

Reputation: 10815

on what basis relationship between tables are defined

I have a question, if two tables in database are from different entities then how we define relationship between them. i mean can we use some foreign key or any thing to define relationship between them. or we have to create a third table

Upvotes: 0

Views: 126

Answers (2)

onedaywhen
onedaywhen

Reputation: 57063

There is a design principle that states that a table either defines an entity or a relationship but not both. Therefore, use a third table to model the relationship between your two entities -- yes, even if it is 1-1 or 1-N -- noting that the relationship itself may have its own attributes.

Upvotes: 0

tucaz
tucaz

Reputation: 6684

It depends on what kind of relationship you have. If it´s a 1-1 or 1-N then you will only add foreign key column on the respective table. If you need a N-N (aka N-M) you will need a third table.

Upvotes: 2

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