I have the following query:
SELECT DISTINCT "EVALA112"("S#") AS "^" FROM "S" ORDER BY "S#" ASC ;
[This is generated code, not hand-written. The table S is from CJ Date
sample data.]
This query appears to work correctly. The function is an aggregation, and
requires the data to be sorted.
This same query fails in Postgres with: "for SELECT DISTINCT, ORDER BY
expressions must appear in select list".
In effect the reason is that a query in this form requires two sort
operations, and a single query can have only one. To get this to work
correctly, I shall either drop the DISTINCT or turn the second part into a
subselect. That I understand.
The question is: how does Sqlite interpret this query? Why is it not an
error? Is it because the query returns a single result, which does not
require a sort?
Regards
David M Bennett FACS
Andl - A New Database Language - andl.org
