RE: Subquery

Jared,

At least with O8i, that's true in about 60-70% of the time. I have found it better to use subqueries instead of joins when that's what you mean. In some cases the optimizer can eliminate a sort step when using sub-queries instead of a join and other times it processes less data.

Sometimes an IN subquery is faster, other times an EXISTS subquery is faster. The point is, you have to try the query all 3 ways.

In this case, I suspect that a subquery will be much faster than the join. (Because of the rownum = 1 restriction)  

Kevin

-----Original Message-----
Sent: Tuesday, May 29, 2001 3:11 PM
To: Multiple recipients of list ORACLE-L

Why change it to subqueries?

The optimizer will just turn it back into a join anyway.

Jared

On Tuesday 29 May 2001 05:15, Roland.Skoldblom_at_ica.se wrote:
> Hallo you DBAs
>
> How can I write this sql query using subqueries?
>
> SELECT pbk.nielsenart.varunamn, pbk.nielsenart.strl,
> pbk.nielsenart.varutxt, null, pbk.nielsenart.vgrp,
> rik2.hierarki_tekst.tekst, null, pbk.sortiment_vgrp.sortiment,
> pbk.nielsenart.art_grp, pbk.nielsenart.art_ugrp, null FROM
> pbk.nielsenart,pbk.sortiment_vgrp,rik2.hierarki_tekst, pbk.rapporttmp
WHERE
> pbk.nielsenart.vgrp=rik2.hierarki_tekst.vgrp
> AND pbk.sortiment_vgrp.vgrp=pbk.nielsenart.vgrp
> AND rik2.hierarki_tekst.sett_id=2
> AND rik2.hierarki_tekst.landkode=46
> AND pbk.nielsenart.ean=pbk.rapporttmp.EAN
> AND ROWNUM=1
>
>
> Roland Sköldblom

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