From the HTML docs:
"The referenced columns must be the columns of a unique or primary key
constraint in the referenced table."
I personally don't know of a work around. Maybe some of the others do.
On Thursday 15 January 2004 10:56 am, Victor Spång Arthursson wrote:
> New to foreign keys and have some questions…
>
> The first is, i have a language table with a primary key on the fields
> lang and relid:
>
> relid | lang | text
> -------+------+-------------
> 11111 | uk | hello
> 11111 | dk | hej
> 11111 | de | guten tag
> 11112 | uk | world
> 11112 | dk | værld
>
> In another table, texts, I have the following:
>
> id | text
> -------+------+
> 4 | 11112 |
>
> What I want to do is to create a foreign key between the two tables.
> But trying to do so, with the following syntax, I get the following
>
> error message:
> > ALTER TABLE varer ADD CONSTRAINT varenavn FOREIGN KEY (varenavn)
>
> REFERENCES languages(relid) MATCH FULL ON DELETE CASCADE;
>
> >ERROR: there is no unique constraint matching given keys for
>
> referenced table "languages"
> tostipippitest=#
>
> Can't i create a Foreign key to a field that is not defined as UNIQUE?
>
> And if so, are there any other approach to solve this problem?
>
> Sincerely
>
> Victor
>
> PS If someone has a link to a good tutorial I would love to have it DS
>
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