In article <[EMAIL PROTECTED]>,
Morten Egan <[EMAIL PROTECTED]> writes:
> Well, it might not be SQL standard, but most databases out there allow
> you to use the alias in your where clauses. It helps make the sql more
> readable, and it shouldn't be that hard to add this feature to the
> parser, so it can translate that alias back to the original row-source
> selection, during parse time.
At least PostgreSQL does not allow that. However, there's a SQL
standard solution: derived tables.
SELECT name, distance
FROM (
SELECT name,
SQRT(POWER((lat - 39.039200), 2) +
POWER((lon + 95.689508), 2)) AS distance
FROM cities
) AS x
WHERE distance < 1
ORDER BY distance
LIMIT 10;
This works in MySQL 4.1.x, and a good query planner would be able to
optimize it properly.
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