Re: left join in TIBDataSet

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#11218

From: Harun Bolat
Date: Wed, 11 Dec 2002 19:18

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> SELECT ID, ID_TCosto, Descripcion, Valor, Accion
>     FROM COSTO C
>     LEFT JOIN TCOSTO TC
>     ON C.ID_TCOSTO = TC.ID_TCOSTO
>     WHERE C.ID = :ID
> 1) I didn't specify in which table is each field. Should I?

yes but all field that you select have to belong only one table. for example
if ID_TCOSTA field found COSTA and TCOSTO tables , select statement raise
error.

> 2) what's the difference with:

> SELECT C.ID, C.ID_TCosto, TC.Descripcion, C.Valor, TC.Accion
>     FROM COSTO C,  TCOSTO TC
>     WHERE C.ID = :ID and C.ID_TCOSTO = TC.ID_TCOSTO

 SELECT ID, ID_TCosto, Descripcion, Valor, Accion
     FROM COSTO C
     JOIN TCOSTO TC    ON C.ID_TCOSTO = TC.ID_TCOSTO
     WHERE C.ID = :ID

 if drop left, results are same but first sql (join SQL) execution time less
than second.
but with left clause first sql result set maybe different.

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Subject: Re: left join in TIBDataSet
Date: Wed, 11 Dec 2002 21:18:21 +0200
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