mowinom_at_hotmail.com wrote:
> On 20 Nov, 11:25, Frank van Bortel <frank.van.bor..._at_gmail.com> wrote:
>> mowi..._at_hotmail.com wrote:
>>> Hello all,
>>> I have the following task: I have a table with two fields, ISBN
>>> (NUMBER 9), TITLE and PERIODICAL_OWNER (NUMBER 9). I am trying to
>>> create a trigger that checks on insert, that the ISBN being entered is
>>> not already in the table but if it does, it must exist in the
>>> PERIODICAL_OWNER column.
>>> So, if the new ISBN being entered is already in the table, it has to
>>> be in the PERIODICAL_OWNER column in order for it to be accepted. I am
>>> new to PL/SQL and have tried writing a trigger but it's not working.
>>> Here it is:
>>> IF :New.ISSN = :Old.ISSN And
>>> :New.ISSN NOT IN (:Old.Tidsskriftnr_eier) THEN
>>> RAISE_APPLICATION_ERROR(-20070, 'ERROR>>' ||
>>> ' PERIODICAL:' ||
>>> ' For ISSN that already exists in the basen, it' ||
>>> ' must exist in periodicald to be accepted.');
>>> ELSE
>>> :New.ISSN := :New.ISSN;
>>> END IF;
>>> Thank you in advance for your help
>>> --
>>> Me
>> Ever heard of modeling and normalization?
>>
>> You have two tables: ISBN is a primary key (which will
>> guarantee uniqueness of ISBN numbers) on the first, and
>> your second table has Periodical as PK, and a foreign key
>> relation to ISBN (mandatory).
>>
>> Really! second class, before Xmas!
>> --
>> Regards,
>> Frank van Bortel
>>
>> Top-posting is one way to shut me up...- Skjul sitert tekst -
>>
>> - Vis sitert tekst -
>
> Thanks Frank, but we are dealing with one table here.
>
> Regards,
> Mark (Me)
Only if you refuse to use a relational database as a relational
database. Frank is suggesting that you use the tool properly.
--
Daniel A. Morgan
Oracle Ace Director & Instructor
University of Washington
damorgan_at_x.washington.edu (replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Tue Nov 20 2007 - 14:59:43 CST
