Обсуждение: Selecting * from the base table but getting the inheriteds columns

Uz.ytkownik James Adams napisa?:
> Hello,
>  
> I have a "baseTable".  I have a number of decendantTables that INHERIT 
> from the base table. 
>  
> I want to do somthing like
>  
> =>select * from baseTable;
>  
> But I want it to return the data in the all the descendant tables along 
> with the extra column that they contain.  How do I do this?
>  

select *, cast(null as varchar) as another_field1, cast(null as int4) as another_field2
from only basetable
union
select *
from descent_table

Isn't it easier to just create baseTable with the same columns as 
descent tables (and fill them with nulls)?

Tomasz Myrta

Yea it would be easier to have everything in one table filling unused with
nulls, but I was trying to avoid that because of the wasted space.

But I think I'll do it that way after all  :~]

Thanks for your help


----- Original Message -----
From: "Tomasz Myrta" <jasiek@klaster.net>
To: "James Adams" <pornstarbatman@hotmail.com>
Cc: <pgsql-sql@postgresql.org>
Sent: Wednesday, October 30, 2002 9:05 AM
Subject: Re: [SQL] Selecting * from the base table but getting the
inheriteds


> Uz.ytkownik James Adams napisa?:
> > Hello,
> >
> > I have a "baseTable".  I have a number of decendantTables that INHERIT
> > from the base table.
> >
> > I want to do somthing like
> >
> > =>select * from baseTable;
> >
> > But I want it to return the data in the all the descendant tables along
> > with the extra column that they contain.  How do I do this?
> >
>
> select
>   *,
>   cast(null as varchar) as another_field1,
>   cast(null as int4) as another_field2
> from only basetable
> union
> select
>   *
> from descent_table
>
> Isn't it easier to just create baseTable with the same columns as
> descent tables (and fill them with nulls)?
>
> Tomasz Myrta
>
>
> ---------------------------(end of broadcast)---------------------------
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>
> http://www.postgresql.org/users-lounge/docs/faq.html
>

On Wed, Oct 30, 2002 at 10:25:17AM +0100, James Adams wrote:
> Yea it would be easier to have everything in one table filling unused with
> nulls, but I was trying to avoid that because of the wasted space.
> But I think I'll do it that way after all  :~]
> Thanks for your help

Don't fret too much about the wasted space: NULL fields set a bit in
a bitmask in the header of the on-disk tuple, so they take up _no_
storage at all.

Ross