Re: case, new column not found

Martín,

> select *,(
> (CASE WHEN titulo LIKE '%Matematica%' THEN 1 ELSE 0 END) +
> (CASE WHEN descripcion LIKE '%Matematica%' THEN 1 ELSE 0 END) +
> (CASE WHEN incumbencia LIKE '%Matematica%' THEN 1 ELSE 0 END) )
> AS encontrados
> FROM admin_view
> WHERE admin_view.nivel=1 AND encontrados > 0;
>
> ERROR: Attribute 'encontrados' not found

The problem is that you're trying to do a WHERE filtering on a
calculated column by its alias. The query engine (correct me if I'm
wrong) wants to evaluate the WHERE clause before the SELECT columns are
returned; as a result, there is no "encontrados" to evaluate as it has
not been calculated yet.

If you really want the results above, you need to:

SELECT admin_view.*, encontrados
FROM admin_view,
(SELECT ((CASE WHEN titulo LIKE '%Matematica%' THEN 1 ELSE 0 END) +
(CASE WHEN descripcion LIKE '%Matematica%' THEN 1 ELSE 0 END) +
(CASE WHEN incumbencia LIKE '%Matematica%' THEN 1 ELSE 0 END) )
AS encontrados, id FROM admin_view) sub_admin
WHERE admin_view.nivel=1
AND admin_view.id = sub_admin.id
AND encontrados > 0;

This forces encontrados to be evaluated first because it's in a
subselect.

A simpler approach would be:

> select *,(
> (CASE WHEN titulo LIKE '%Matematica%' THEN 1 ELSE 0 END) +
> (CASE WHEN descripcion LIKE '%Matematica%' THEN 1 ELSE 0 END) +
> (CASE WHEN incumbencia LIKE '%Matematica%' THEN 1 ELSE 0 END) )
> AS encontrados
> FROM admin_view
> WHERE admin_view.nivel=1 AND
(titulo LIKE '%Matematica%' OR descripcion LIKE '%Matematica%'
OR incumbencia LIKE '%Matematica%');

Which would give you the same results.

-Josh

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