Re: Running Update Problem

From: Chris L. <diversos_at_uol.com.ar>
Date: Mon, 25 Jun 2007 07:16:30 -0700
Message-ID: <1182780990.271937.175190@q69g2000hsb.googlegroups.com>

On 23 jun, 06:03, "pankaj_wolfhun..._at_yahoo.co.in" <pankaj_wolfhun..._at_yahoo.co.in> wrote:
> On Jun 23, 12:04 am, "Chris L." <diver..._at_uol.com.ar> wrote:
>
>
>
>
>
> > On 22 jun, 14:59, "pankaj_wolfhun..._at_yahoo.co.in"
>
> > <pankaj_wolfhun..._at_yahoo.co.in> wrote:
> > > Greeting,
>
> > > I have a table say t1 with structure as (dummy)
>
> > > t1
>
> > > id id1 id2
> > > 1 0 -1
> > > 2 0 -3
> > > 3 8 -4
> > > 4 0 -5
>
> > > I want to:
> > > update t1 set id1=min(id2) where id1=0.
> > > but each id1 should get updated with one value greater than the
> > > previous value.
>
> > > Means, here the min(id2) is -5, so all id1=0 record should get updated
> > > starting with -6, -7, -8 and so on.
>
> > > Output like
>
> > > id id1 id2
> > > 1 -6 -1
> > > 2 -7 -3
> > > 3 8 -4
> > > 4 -8 -5
>
> > > Can anyone help me build this logic?
>
> > > Help would be appreciated
>
> > > TIA
>
> > CREATE TABLE t1 (
> > id NUMBER(2),
> > id1 NUMBER(2),
> > id2 NUMBER(2));
>
> > INSERT INTO t1
> > SELECT 1, 0, -1 FROM dual union
> > SELECT 2, 0, -3 FROM dual union
> > SELECT 3, 8, -4 FROM dual union
> > SELECT 4, 0, -5 FROM dual ;
>
> > UPDATE t1 SET
> > id1=
> > -ROWNUM+(SELECT Min(id2) FROM t1 WHERE id1=0)
> > WHERE id1=0;
>
> > This gives the expected output of your particular example.
>
> > BTW "one value greater" than -5 is -4, not -6 :)- Hide quoted text -
>
> > - Show quoted text -
>
> Thanks David, Chris. That was helpful.
>
> One more point, what if I want to update id based on some group by
> condition.
> Suppose the structure changes to
>
> t1
>
> id id1 id2 sign
> 1 0 -1 A
> 2 0 -3 A
> 3 8 -4 B
> 4 0 -5 B
> 5 0 -5 B
>
> and I would like to apply the same logic grouping on sign.
> Output like
>
> id id1 id2 sign
> 1 -6 -1 A
> 2 -7 -3 A
> 3 8 -4 B
> 4 -6 -5 B
> 5 -7 -5 B
>
> Something like
>
> UPDATE t1
> SET id1=-ROWNUM+(SELECT Min(id2) FROM t1 WHERE id1=0)
> WHERE id1=0
> GROUP BY sign;
>
> Any idea?
>
> TIA
Sorry I don't know enough SQL to do it in one single statement. Here's some PL/SQL code to do it. Basically repeats the update statement for every value of "sign".

CREATE TABLE t1 (
id NUMBER(2),

id1 NUMBER(2),
id2 NUMBER(2),
ssign CHAR(1));

INSERT INTO t1
SELECT 1,   0,       -1,'A' FROM dual union
SELECT 2,   0,       -3,'A' FROM dual union
SELECT 3,   8,       -4,'B' FROM dual union
SELECT 4,   0,       -5,'B' FROM dual union
SELECT 5,   0,       -5,'B' FROM dual ;

BEGIN
  DECLARE
  CURSOR cur_signs is
    SELECT DISTINCT ssign FROM t1;
  min_value NUMBER;

  BEGIN     SELECT Min(id2) INTO min_value FROM t1     WHERE id1=0;

    FOR rrow IN cur_signs LOOP

      UPDATE t1 SET
      id1= min_value - ROWNUM
      WHERE id1=0 AND ssign=rrow.ssign;

    END LOOP;   END;
END;
/ Received on Mon Jun 25 2007 - 09:16:30 CDT