Обсуждение: Need your help

Hi,
I need your help on something. I have to write a
trigger (in sybase) that does this: Everytime a record
gets updated it should update a column in that record
with the current date/time. I am able to do it for the
whole table, but how do I make sure the update happens
only for that record which is being updated? Please
respond.
Thanks a bunch,
Jyotsna.


__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail - only $35 
a year!  http://personal.mail.yahoo.com/

e.g.
Try:

CREATE TABLE emp (   id int4 primary key,   empname text,   salary int4,   last_date datetime,   last_user name);

CREATE FUNCTION emp_stamp () RETURNS OPAQUE AS   BEGINupdate emp set last_date=''now''::timestamp where id=NEW.id;
RETURN NEW;   END;
 
' LANGUAGE 'plpgsql';

CREATE TRIGGER emp_stamp BEFORE UPDATE ON emp   FOR EACH ROW EXECUTE PROCEDURE emp_stamp();    

Jie LIANG

St. Bernard Software
Internet Products Inc.

10350 Science Center Drive
Suite 100, San Diego, CA 92121
Office:(858)320-4873

jliang@ipinc.com
www.stbernard.com
www.ipinc.com

On Mon, 19 Feb 2001, Jyotsna Kypa wrote:

> Hi,
> I need your help on something. I have to write a
> trigger (in sybase) that does this: Everytime a record
> gets updated it should update a column in that record
> with the current date/time. I am able to do it for the
> whole table, but how do I make sure the update happens
> only for that record which is being updated? Please
> respond.
> Thanks a bunch,
> Jyotsna.
> 
> 
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail - only $35 
> a year!  http://personal.mail.yahoo.com/
> 

Jie Liang wrote:
> e.g.
> Try:
>
> CREATE TABLE emp (
>     id int4 primary key,
>     empname text,
>     salary int4,
>     last_date datetime,
>     last_user name);
>
> CREATE FUNCTION emp_stamp () RETURNS OPAQUE AS
>     BEGIN
>    update emp set last_date=''now''::timestamp where id=NEW.id;
>         RETURN NEW;
>     END;
> ' LANGUAGE 'plpgsql';
>
> CREATE TRIGGER emp_stamp BEFORE UPDATE ON emp
>     FOR EACH ROW EXECUTE PROCEDURE emp_stamp();
   Not  sure  if it works this way at all, but the update on emp   table is definitely a wasted scan. And  the
'now'::timestamp  will  be  evaluated at the first function call - never again;   not sure if he wanted that behaviour
either.
       CREATE FUNCTION emp_stamp () RETURNS opaque AS '       BEGIN           new.last_date := now();           RETURN
new;      END;'       LANGUAGE 'plpgsql';
 
   Is the correct trigger for this purpose.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#================================================== JanWieck@Yahoo.com #



_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com