Oracle-L: Re:a simple question about FKs

From: <dgoulet_at_vicr.com>
Date: Tue, 18 Jun 2002 06:03:33 -0800
Message-ID: <F001.004803B5.20020618060333@fatcity.com>

Gene,

In the event of a delete from the parent Oracle has a chance to check the child table(s) to see if the parent is still valid. But since a truncate is really a DDL, not DML, command there is no such chance. Therefore if you want to truncate a table you have to disable the foreign keys. Same thing as dropping a table, except that Oracle provided the 'cascade constraints' qualifier.

Dick Goulet

____________________Reply Separator____________________
Author: Gurelei <gurelei_at_yahoo.com>
Date:       6/18/2002 5:43 AM

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

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Author: Gurelei
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