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37

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+1  Q: 

Cardinality in PostgreSQL

I have a UML diagram of what I need my database schema to look like. This diagram includes roles and cardinality. How can I enforce cardinality in Postgres?

A: 

Cardinality is enforced by using constraints.

http://www.postgresql.org/docs/8.1/static/ddl-constraints.html

Robert Harvey  2010-06-28 18:53:01
Could you please give me an example of such a constraint?
nix  2010-06-28 19:00:01
What kind of cardinality are you trying to constrain? Range, uniqueness (another kind of range), or one-to-many joins? The link I provided has good examples of all three.
Robert Harvey  2010-06-28 19:01:49
Thanks. I've looked at them.
nix  2010-06-28 21:20:19

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