Re: Which query is more correct?

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On Fri, Nov 20, 2009 at 04:41:58PM -0600, LAMP wrote:
> Hi,
> I need to pull all records from the table Registrants they are NOT
> in the table ToBeRecleared
> 
> Registrants.Reg_ID is PK
> ToBeRecleared.tbrc_Reg_ID is PK
> 
> Which query is more correct?
> 
> SELECT r.*
> FROM registrants r
> where r.reg_status=1 AND r.reg_id NOT IN (SELECT tbrc_reg_id FROM
> toberecleared)
> 
> 
> SELECT r.*
> FROM registrants r
> where r.reg_status=1 AND (SELECT count(*) FROM toberecleared where
> tbrc_reg_id=r.reg_id) = 0
> 
> I checked explain of bot queries - but can't "read" them.  :-)

SELECT t1.*
FROM registrants t1
LEFT JOIN ToBeRecleared t2 on t1.reg_id = t2.tbrc_reg_id
where t2.tbrc_reg_id is NULL

-- 
"Every major horror of history was committed in the name of an
 altruistic motive." -- Ayn Rand, The Fountainhead, 1943
    Rick Pasotto    rick@xxxxxxxx    http://www.niof.net

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