>
> It seems that some database engines don't let one use
> alias columns within WHERE clauses for some odd
> reason. I often get "invalid column" when I try to do
> this. Thus, I have to resort to the "native" name
> with a table/entity qualifier in WHERE clauses.
> This works, but makes generated
> criteria code more difficult to manage because
> the result set column name differs from the
> criteria column name.
This is not the odd reason, in my opinion.
The sequence of evaluation of each clause in a select statement is
defined by SQL Standards, and perhaps implemented strictly in some
DBMSs.
Without these defined sequence, the result of a query may be
unpredictable or cause error.
For example, an expression in a select clause may cause an error if
evaluated appropriately before filtering out rows by where clause.
Received on Tue May 14 2002 - 07:33:02 CDT
