RE: a simple question about FKs

From: Stephane Faroult <sfaroult_at_oriolecorp.com>
Date: Tue, 18 Jun 2002 06:18:18 -0800
Message-ID: <F001.004803E9.20020618061818@fatcity.com>

('binary' encoding is not supported, stored as-is)
>
>Hi.
>
>I was trying to truncate a table, which is a parent
>
>to two other tables (its PK is referred to by two
>FKs
>from two other tables). These "other" tables are
>empty.
>When I tried to truncate the parent table, however,
>I
>got an error message ORA-02266: unique/primary keys
>in
>table referenced by enabled foreign keys. I thought
>
>that as long as the child tables are empty, the RI
>shouldn't matter, but I had to disable the FKs
>before
>being able to truncate the table. Is that the way
>Oracle checks truncates (no enabled RIs even if the
>
>tables are empty) or did I do something
>incorrectly?
>
>thanks
>
>Gene
>

 Gene,

   Your assumption is correct. Since TRUNCATE doesn't go through all rows (as DELETE) and cannot therefore check rows one by one, this is how it is implemented. BTW, do not be fooled by TRUNCATE even if its result is for the superficial mind the same as a DML command (DELETE): it is a DDL command. Therefore, Oracle checks exactly the same as with DROP.

Regards,

Stephane Faroult
Oriole

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroul
  INET: sfaroult_at_oriolecorp.com

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Received on Tue Jun 18 2002 - 09:18:18 CDT