Peter Otten wrote:
> select * from (select alpha from demo union all select alpha from demo) order 
> by alpha
> decltype: (null)
>
> select * from (select alpha from demo union all select alpha from demo)
> decltype: custom
>
> Even taking http://sqlite.org/c3ref/column_decltype.html
> """
> If this statement is a SELECT statement and the Nth column of the returned
> result set of that SELECT is a table column (not an expression or subquery)
> then the declared type of the table column is returned. If the Nth column of
> the result set is an expression or subquery, then a NULL pointer is
> returned.
> """
> into account I would have expected either NULL or "custom" for both queries.

The first query uses a temporary table for sorting.  The column in that
temporary table does not have a declared type.

The second query returns the values directly from the underlying table
column, so the declared type is also from that table.


Regards,
Clemens
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