Re: Condition in a calculated field - Mailing list pgsql-novice

From David G Johnston
Subject Re: Condition in a calculated field
Date
Msg-id 1410288537370-5818355.post@n5.nabble.com
Whole thread Raw
In response to Condition in a calculated field  (JORGE MALDONADO <jorgemal1960@gmail.com>)
Responses Re: Condition in a calculated field  (JORGE MALDONADO <jorgemal1960@gmail.com>)
List pgsql-novice
JORGE MALDONADO wrote
> Can I use a calculated field in a WHERE condition of a SELECT statement? I
> get a "column 'total' does not exist" error when I run the statement
> below.
> 'total' is a field generated by a SUM and I want to use it in the WHERE
> condition.
>
> SELECT
>   facturas.fce_id,
>   facturas.fce_numero_factura,
>   facturas.fce_fecha,
>   compradores.com_nombre,
>   facturas.fce_subdivision,
>   facturas.fce_valor_comercial,
>   SUM(facsub.fce_valor_comercial) AS total
> FROM
>   trafico.facturas_exportacion facturas
>   INNER JOIN trafico.cat_compradores compradores ON
> (facturas.fce_comprador
> = compradores.com_clave)
>   INNER JOIN trafico.facturas_exportacion facsub ON (facturas.fce_id =
> facsub.fce_id_factura_original)
> WHERE
>   facturas.fce_subdivision = true AND facturas.fce_valor_comercial > total
> GROUP BY facturas.fce_id,compradores.com_clave
>
> Respectfully,
> Jorge Maldonado

WHERE clause is pre-grouping.

What you want is the HAVING clause - though you have to repeat the
expression (e.g., col > sum(...) ) as opposed to referring to it by name
(e.g., col > total).

http://www.postgresql.org/docs/devel/static/sql-select.html

David J.




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