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Learner1

One-to-one relationships

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Hello,

I have searched the file maker 8 user guide and many websites but can't find any thing about one-to-one relationships in filemaker. Does anyone have an idea about how I can set this kind of relationships.

Thanks in advance ;)

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One to one relationships aren't very useful. An example:

We have a bunch of information about "People". We also have "unique ID numbers" of which each person can only have one, and each ID number can only be associated with one person: a typical one-to-one relationship.

One-to-one information could be kept in a separate table, but because it's never duplicated, and there must always exactly the same amount of ID numbers as there are people, it's easier and more correct to store the IDs in a field in the same table. Hence, information that exists in a one-to-one relationahip is about the same entity and needs to be in the same table.

Should you be asking about one-to-many or many-to-many rekationahips? These are useful and interesting (particularly m2m).

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I'll have to disagree with Vaughn about 1:1 relationships. They are both useful and appropriate in FMP.

Specifically, 1:1 relationships are used for optional attributes about an entity (e.g. not every employee drives a car to work so attributes about the car make, model, color, and marker plates would be stored in a separate table). They are also used for representing supertype/subtype relationships.

In supertype/subtype relationships I prefer to use the same primary key for both tables, allowing auto-create through the relationship for population of the primary key in the subtype table.

Their setup is fairly straightforward. Don't be confused by the graph though; those lines and crows feet don't necessarily represent the relationship type you see.

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Thank you to both of you for your advice. I actually do need to seperate the 2 entities into 2 tables.

It's the graph that was confusing me.

thanks again ;)

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