Posted By: Libb (Libor) on 'CZdatabases'
Title:     Re: zajimavost
Date:      Thu Sep  5 06:44:36 2002

select count(*) from B where id in (select distinct id from A)

Takhle bych to delal ja - pro MS SQL

> Ahoj.
> 
>   tab A                  tab B
>   id                     id
>   1                      1
>   1                      2
>   1                      3
>   2
>   2
> 
> A ted jak zjistit pocet zaznamu v B, ktere maji odkaz v tabulce A?
> 
>   SELECT COUNT(*) FROM a,b WHERE a.id = b.id 
> 
> vrati hodnotu 4. Nas sef nastesti nekde vyhrabal:
> 
>   SELECT COUNT(DISTINCT b.id) FROM a,b WHERE a.id = b.id
> 
> a to vrati 2 :-)  Je to Informix specific, nebo to funguje i jinde?
> Jovo.

                                                                      Libb