Re: HELP with a Query

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Re: HELP with a Query

От:
Martijn van Oosterhout <kleptog@svana.org>
Дата:
On Sat, Feb 21, 2004 at 05:20:51PM +0900, Alex wrote:
> Hi,
> I need some help with a query.
> I use a reference table to lookup some codes. Everything works well if the 
> reference table contains a reference but the query fails if no reference 
> fails (Z.ref_code=123456). What I need to is either return 0 or null into 
> Z.prim_exch if no reference can be found. Whats the best way to do that ? I 
> tried a sub query but also did not succeed.

Lookup an SQL site about OUTER JOINS. Should do what you want.

-- 
Martijn van Oosterhout      http://svana.org/kleptog/
> If the Catholic church can survive the printing press, science fiction
> will certainly weather the advent of bookwarez.
>    http://craphound.com/ebooksneitherenorbooks.txt - Cory Doctorow

HELP with a Query

От:
Alex <alex@meerkatsoft.com>
Дата:
Hi,
I need some help with a query.
I use a reference table to lookup some codes. Everything works well if the reference table contains a reference but the query fails if no reference fails (Z.ref_code=123456). 
What I need to is either return 0 or null into Z.prim_exch if no reference can be found. Whats the best way to do that ? I tried a sub query but also did not succeed.


SELECT A.sec_code,A.exch_code,A.price_date,Z.prim_exch,
   CASE
     WHEN A.exch_code = Z.prim_exch THEN 1
     ELSE 0
   END AS is_prim
FROM price_hist AS A, references AS Z
WHERE   A.price_date <= '20040219' AND A.sec_code=123456 AND Z.ref_code=123456 LIMIT 10;

Thanks for any help.
Alex
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