Re: [Firebird-devel] Upper and column alias

[Dmitry Y. <fir...@ya...>]

Leyne, Sean wrote:
> 
>> And tomorrow you will ask to use aliases in the WHERE clause and then
>> elsewhere. I was always against this "feature".
> 
> Why?
> 
> It would seem to me to be a logical step.
> 
> After all, defining an alias creates a 'virtual' field, why not be able
> to refer to this field elsewhere in the SELECT statement?

With this approach, we end with many queries becoming ambiguous, e.g.:

CREATE TABLE T (A INT, B INT);
SELECT A AS B FROM T WHERE B = 0;

We're already affected by this issue in v2.0 for GROUP BY / ORDER BY, as 
we throw an error for queries that were perfectly valid before. And I 
don't want it to go further.

IMO, those needing this feature should just express their wishes in code 
explicitly using a derived table with named derived fields.


Dmitry