Re: TRIGGERS

From: Kean Jacinta <jacintakean_at_yahoo.com>
Date: Wed, 18 May 2005 09:33:43 -0700 (PDT)
Message-ID: <20050518163343.37401.qmail@web52902.mail.yahoo.com>

HI,

here is what i have written in trigger body, i am really stuck here. help me up , it;s still not working . System still complain about the unique key error. **:(

DECLARE
REFCOUNT NUMBER;
DUP_VAL_ON_INDEX EXCEPTION;

  TEMP                NUMBER;

BEGIN
IF INSERTING THEN

      
   LOOP      
      SELECT COUNT(*) INTO REFCOUNT
      FROM myclass
      WHERE :NEW.id = id;
                  
      IF REFCOUNT > 0 THEN --RECORD EXISTED IN
DATABASE
      SELECT myclass_seq.NEXTVAL INTO TEMP FROM DUAL;
      END IF;
             
      
  END LOOP;    
      
      IF :NEW.ID IS NULL THEN
      
            
      SELECT myclass_SEQ.NEXTVAL 
      INTO :NEW.ID 
      FROM DUAL;
      END IF;

END IF; --MAIN IF END; Note : have no idea how to use the exception handler

JKean

david wendelken <davewendelken_at_earthlink.net> wrote:

> If you really want to handle that, you have three
> choices:
>
> 1) Live with it. If you have a program that
> assigns the id values for you, it should be getting
> its next value from the sequence also. If you do
> that, this just isn't a problem in real life. If
> you aren't willing to ALWAYS get the next id value
> from a sequence, you probably shouldn't be using a
> sequence at all.
>
> 2) Relatively simple, partial solution. Use a
> pre-statement trigger on insert, have it grab the
> next sequence value and verify that the record for
> that sequence number is not already in the table.
> If it is, get the next sequence value until you find
> an empty one. Assume that all the ones after that
> are ok from then on. Ignore the fact taht you throw
> away a sequence number each time you do a statement.
> Remember, I said *partial* solution.
>
> 3) Read up on mutating table errors and autonomous
> transactions. This will take you awhile to read and
> experiment with. We have time to help with specific
> problems, but not to write it for you.
> Ask again after you've read that material and are
> are stuck.
>
>
>
> -----Original Message-----
> From: Kean Jacinta <jacintakean_at_yahoo.com>
> Sent: May 18, 2005 8:02 AM
> To: david wendelken <davewendelken_at_earthlink.net>
> Subject: Re: TRIGGERS
>
> david,
>
> :P oh i see . I am so blur. My concern,
>
> ID
> ---
> 1 <-- autogenerated
> 2 <-- autogenerated
> 3 <-- autogenerated
> 4 <-- manually created
> 5 <-- manually created
>
> My current sequence stay at : 3 , if i issued an
> autotgenerated insert again it will surely prompt
> unique id alrdy existed... or some sort of database
> error. How can then trigger being smart enough to
> silently generate autoid 6 without raising error ?
>
> I am very close to my objectives alrdy :P
>
> Thank in advance
> Jkean
>

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Received on Wed May 18 2005 - 12:38:23 CDT