Re: CONSTRAINT ... FOREIGN KEY

Not, yet;-(
For me the connection between two tables - database relation - based on two
KEYs one in the "FOREIGN" table one in the "NATIV" table, other way how to
deside which rows are "linked" to foreign row (from this point of view
"parent" or many-to-one relation). Other words - KEYs on both tables are
must be!
In SQL language it is not obviose, that I cretae a FOREIGN KEY- REFERENCES
to a UNIQUE column in other table, which is not a PRIMERY KEY or UNIQUE
INDEX in foreign table. Other way how server will find, as quickly as
possible, the related row in the related table?
Sincerelly
   tovis

PS: also if I create a column as UNIQUE how the server will deside that
newly inputed value is unique to this column, without create a key/index -
linear search on several million records?!

----- Original Message -----
From: <operationsengineer1@yahoo.com>
To: "tövis" <tovises@freemail.hu>; "pgsql novice"
<pgsql-novice@postgresql.org>
Sent: Tuesday, May 03, 2005 4:30 AM
Subject: Re: [NOVICE] CONSTRAINT ... FOREIGN KEY


> --- tövis <tovises@freemail.hu> wrote:
>> Creating/adding a "FOREIGN KEY" creates any "real"
>> key sequencies?
>
> tovis, i'm not sure of the technical details, but a
> link is created between the foreign key and the column
> it references.
>
>> Foreign key constraint became a key - seem to me,
>> but what about the foreign table, there is also
>> created a "seemless" key or I should create somthing
>> (of course if it is not the primery key) - index?
>> Sincerelly
>>     tovis
>
> the foreign key should most definitely reference
> another column in another table.
>
> your question is a little hard for me to understand -
> i hope i answered it.
>
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