Re: Two questions in Oracle...

From: <>
Date: Thu, 26 Aug 1999 13:57:17 GMT
Message-ID: <7q3h3m$nvc$>

In article <>,   Jimmy <> wrote:
> Hello all,
> I have two questions: (in Oracle 7.3.3)
> 1) Why the following SQL statement returns 'aaa'?
> select 'aaa' from dual where 'LOW_D_LIMIT' like 'L_%';
> Is '_' means special character? 'LOW_D_LIMIT' not contains the
> string like 'L_' and it should return 'no rows returned' I
> think......... but it returns 'aaa'....
Yes that is because the underscore is the single position wildcard so you asked to return all rows that start with L followed by any one character followed by any characters so you got what you asked for.

> 2) I want to develop a trigger like this:
> create or replace trigger testing
> after update or insert or delete on aaa
> begin
> if updating then
> if updating(fieldA) then
> pro1;
> end if;
> pro_all;
> elsif inserting then
> ...
> elsif deleting then
> ...
> end if;
> end;
> /
> If update column fieldA, then do pro1 and pro_all Other columns
> updating do only pro_all.
> However, errors in creating this trigger.... Is it possible to
> which column is updated in the updating part? I cannot do this:
> create or replace trigger testing
> after update(fieldA) or insert or delete on aaa
> ...
> since this trigger only fired if fieldA is updated.
> Thanks,
> Jimmy
I am not sure what is wrong with your trigger but I believe that you can do what you want. You will need to identify you table column names with old.column_name or new.column_name so Oracle knows which one you are referring to.

Mark D. Powell  -- The only advice that counts is the advice that
 you follow so follow your own advice --

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Received on Thu Aug 26 1999 - 15:57:17 CEST

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