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Thread: No DIVIDE Operator

No DIVIDE Operator

From
Joerg Fischer
Date:
Hi!

Consider the following szenario:

Two Tables:

create table Person (   name text,   prename text,   street text,   town text
);

create table Officer (   name text,   prename text,   bureau text
);

So, every Officer is a Person. Now, I would like to get all persons
except for Officers.

If there would be a divide operator, I could write

select name, prename from Person divide select name, prename from
Officer;

without it, however, things get really complicated:

select name, prename from Person where prename not in ( select prename
from Officer where Officer.name = Person.name );

This is an easy example. However, I have to deal with about 10 tables in
a corresponding way.

Any better idea? Will there be a divide operator in PGSQL soon?

Thanks!

Regards

Joerg Fischer

Re: [SQL] No DIVIDE Operator

From
Chris Bitmead
Date:
Isn't that what EXCEPT does?

chris=> create table foo (text text);
CREATE
chris=> insert into foo values('aaa');
INSERT 22153 1
chris=> insert into foo values('bbb');
INSERT 22154 1
chris=> insert into foo values('ccc');
INSERT 22155 1
chris=> select * from foo EXCEPT select 'aaa';
text
----
bbb 
ccc 
(2 rows)



> If there would be a divide operator, I could write
> 
> select name, prename from Person divide select name, prename from
> Officer;
> 
> without it, however, things get really complicated:
> 
> select name, prename from Person where prename not in ( select prename
> from Officer where Officer.name = Person.name );
> 
> This is an easy example. However, I have to deal with about 10 tables in
> a corresponding way.
> 
> Any better idea? Will there be a divide operator in PGSQL soon?
> 
> Thanks!
> 
> Regards
> 
> Joerg Fischer

-- 
Chris Bitmead
http://www.bigfoot.com/~chris.bitmead
mailto:chris.bitmead@bigfoot.com

Re: [SQL] No DIVIDE Operator

From
Joerg Fischer
Date:
Chris Bitmead wrote:
> 
> Isn't that what EXCEPT does?

Maybe the operator is named differently between different database
systems. Anyway, as far as I am concerned, PGSQL lacks it. Or
(hopefully), am I wrong??

Regards

Joerg Fischer

> chris=> create table foo (text text);
> CREATE
> chris=> insert into foo values('aaa');
> INSERT 22153 1
> chris=> insert into foo values('bbb');
> INSERT 22154 1
> chris=> insert into foo values('ccc');
> INSERT 22155 1
> chris=> select * from foo EXCEPT select 'aaa';
> text
> ----
> bbb
> ccc
> (2 rows)
> 
> > If there would be a divide operator, I could write
> >
> > select name, prename from Person divide select name, prename from
> > Officer;
> >
> > without it, however, things get really complicated:
> >
> > select name, prename from Person where prename not in ( select prename
> > from Officer where Officer.name = Person.name );
> >
> > This is an easy example. However, I have to deal with about 10 tables in
> > a corresponding way.
> >
> > Any better idea? Will there be a divide operator in PGSQL soon?
> >
> > Thanks!
> >
> > Regards
> >
> > Joerg Fischer

Re: [SQL] No DIVIDE Operator

From
Chris Bitmead
Date:
Joerg Fischer wrote:
> 
> Chris Bitmead wrote:
> >
> > Isn't that what EXCEPT does?
> 
> Maybe the operator is named differently between different database
> systems. Anyway, as far as I am concerned, PGSQL lacks it. Or
> (hopefully), am I wrong??

Well Postgres has EXCEPT. Is that what you want?

> 
> Regards
> 
> Joerg Fischer
> 
> > chris=> create table foo (text text);
> > CREATE
> > chris=> insert into foo values('aaa');
> > INSERT 22153 1
> > chris=> insert into foo values('bbb');
> > INSERT 22154 1
> > chris=> insert into foo values('ccc');
> > INSERT 22155 1
> > chris=> select * from foo EXCEPT select 'aaa';
> > text
> > ----
> > bbb
> > ccc
> > (2 rows)
> >
> > > If there would be a divide operator, I could write
> > >
> > > select name, prename from Person divide select name, prename from
> > > Officer;
> > >
> > > without it, however, things get really complicated:
> > >
> > > select name, prename from Person where prename not in ( select prename
> > > from Officer where Officer.name = Person.name );
> > >
> > > This is an easy example. However, I have to deal with about 10 tables in
> > > a corresponding way.
> > >
> > > Any better idea? Will there be a divide operator in PGSQL soon?
> > >
> > > Thanks!
> > >
> > > Regards
> > >
> > > Joerg Fischer

-- 
Chris Bitmead
http://www.bigfoot.com/~chris.bitmead
mailto:chris.bitmead@bigfoot.com

Re: [SQL] No DIVIDE Operator

From
Bruce Momjian
Date:
> Joerg Fischer wrote:
> > 
> > Chris Bitmead wrote:
> > >
> > > Isn't that what EXCEPT does?
> > 
> > Maybe the operator is named differently between different database
> > systems. Anyway, as far as I am concerned, PGSQL lacks it. Or
> > (hopefully), am I wrong??
> 
> Well Postgres has EXCEPT. Is that what you want?

I think we only got EXCEPT in 6.5 beta, so he may not have it yet.
--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026

Re: [SQL] No DIVIDE Operator

From
Joerg Fischer
Date:
Chris Bitmead wrote:
> 
> Joerg Fischer wrote:
> >
> > Chris Bitmead wrote:
> > >
> > > Isn't that what EXCEPT does?

> > Maybe the operator is named differently between different database
> > systems. Anyway, as far as I am concerned, PGSQL lacks it. Or
> > (hopefully), am I wrong??
> 
> Well Postgres has EXCEPT. Is that what you want?

AFAIK, EXCEPT is included in version 6.5beta1. Monday, I installed that
one. Now it works! Great! Thanks!

Regards

Joerg Fischer