On Jun 9, 2008, at 11:34 AM, Christoph Zwerschke wrote:
>
> I need to order a table by start and end dates, where null values
> should
> be interpreted as "prior to all values" for start dates and "later
> than
> all values" for end dates.
>
> This could be realized with "nulls first", "nulls last", but it seems
> this did not make it into SQLAlchemy yet (ticket #723).
>
> A workaround (for PostgreSQL) would be something like this:
>
> order_by coalesce(start, timestamp '-infinity'),
> coalesce(end_date, timestamp 'infinity')
>
> But I don't find how to construct this with SQLAlchemy. Any ideas? Any
> better solutions?
I tend to use a CASE statement for this: CASE WHEN x IS NULL THEN 0
ELSE x . We have case() construct for that.
For your version, use func.coalesce(start, literal_column("timestamp '-
infinity'")) .
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