mysql composite unique on FK's

Posted by m2o on Stack Overflow See other posts from Stack Overflow or by m2o
Published on 2010-04-07T10:05:31Z Indexed on 2010/04/07 10:13 UTC
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Filed under:

mysql

|

foreign-keys

|

constraints

I want to implement the following constraints in mysql:

create table TypeMapping(
    ...
    constraint unique(server_id,type_id),

    constraint foreign key(server_id) references Server(id),

    constraint foreign key(type_id) references Type(id)
);

This throws a 'ERROR 1062 (23000): Duplicate entry '3-4' for key 'server_id'' when I issue an insert/update that would break the constraint. Is this type of constraint even possible? If so how? Thank you.

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