MySQL Relationships Question?

RecoilUK · 08-02-2001, 05:08 PM

Hi guys, hows it going

Just a quick one this time

I know how to define foreign key relationships in MySQL but i,m wondering if you also need to define the type of relationship i.e. one to one,one to many or many to many relationships?

Does MySQL support these or is it controlled by PHP at the input terminal?

Any help would be appreciated.

Cheers Guys

Stay Kewl

RecoilUK

acid_kewpie · 08-02-2001, 06:05 PM

You do not explicitly define the type of relationship under sql. Using a foreign key you will create a 1:M relationship, which can then be restricted back to 1:1 by setting unique for the foreign key as well as the primary being naturally unique.

M:M keys are only theoretical, and need to be modelled with 2 M:1 relationships connected via an intermediate pairs table.

Well, that's my Database theory knowledge i learnt last year.. only go 60% in the exam tho.....

chris
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