Обсуждение: double linked list

Hi folks!,

I've got a table called 'link_t' containing a collection of seller -
buyer relations between two parties.

sql> select * from link_t

S B
- -
C X
A B
B C
C D
D E

5 rows selected.

I am looking for a select statement that returns the concatenation of
seller - buyer relations between the first seller 'A' and the last
buyer 'B'.

the result should be

S B
- -
A B
B C
C D
D E

Currently I fumbling around with self joins but haven't figured out
yet.
Any suggestions

Many tanks in advance

Cheers

Juergen

Juergen wrote:

> Hi folks!,
>
> I've got a table called 'link_t' containing a collection of seller -
> buyer relations between two parties.
>
> sql> select * from link_t
>
> S B
> - -
> C X
> A B
> B C
> C D
> D E
>
> 5 rows selected.
>
> I am looking for a select statement that returns the concatenation of
> seller - buyer relations between the first seller 'A' and the last
> buyer 'B'.
>
> the result should be
>
> S B
> - -
> A B
> B C
> C D
> D E
>
> Currently I fumbling around with self joins but haven't figured out
> yet.
> Any suggestions
>
> Many tanks in advance
>
> Cheers
>
> Juergen

Look at the CONNECT BY built-in function.

Daniel Morgan

I've seen CELKO's reply and find it very useful.
But I cannot find anything about

> BEGIN ATOMIC
> DECLARE rightmost_spread INTEGER;
>
> SET rightmost_spread
>     = (SELECT rgt
>          FROM Frammis
>         WHERE part = 'G');
> ...

Is this PostgreSQL at all? Any hints welcome.

Regards, Christoph

On Thursday 30 January 2003 07:10, Christoph Haller wrote:
> I've seen CELKO's reply and find it very useful.
> But I cannot find anything about
>
> > BEGIN ATOMIC
> > DECLARE rightmost_spread INTEGER;
> >
> > SET rightmost_spread
> >     = (SELECT rgt
> >          FROM Frammis
> >         WHERE part = 'G');
> > ...
>
> Is this PostgreSQL at all? Any hints welcome.

Mr Haller

No, this is a dialect SQL-92 (SQL-99?) that Mr Celko uses for his
examples since his solutions are vendor nutral. He is big on standards,
so posting using the standard is his way of boosting them.

BEGIN ATOMIC  is BEGIN in PG.

I am not sure how to declare a variable in PG in normal SQL. I don't do
it that often, but when I do I do this:

CREATE TEMPORARY TABLE Rightmost_Spread
AS SELECT rightmost_spread    FROM Frammis   WHERE part = 'G';

I wonder what the alterntatives are?

Alan Gutierrez - ajglist@izzy.net
http://khtml-win32.sourceforge.net/ - KHTML on Windows

>
> On Thursday 30 January 2003 07:10, Christoph Haller wrote:
> > I've seen CELKO's reply and find it very useful.
> > But I cannot find anything about
> >
> > > BEGIN ATOMIC
> > > DECLARE rightmost_spread INTEGER;
> > >
> > > SET rightmost_spread
> > >     =3D (SELECT rgt
> > >          FROM Frammis
> > >         WHERE part = 'G');
> > > ...
> >
> > Is this PostgreSQL at all? Any hints welcome.
>
> Mr Haller
>
> No, this is a dialect SQL-92 (SQL-99?) that Mr Celko uses for his
> examples since his solutions are vendor neutral. He is big on
standards,
> so posting using the standard is his way of boosting them.
>
> BEGIN ATOMIC  is BEGIN in PG.
>
> I am not sure how to declare a variable in PG in normal SQL. I don't
do
> it that often, but when I do I do this:
>
> CREATE TEMPORARY TABLE Rightmost_Spread
> AS SELECT rightmost_spread
>      FROM Frammis
>     WHERE part = 'G';
>
> I wonder what the alternatives are?
>
plpgsql is the best I can think of.
And thanks for the quick reply.

Regards, Christoph