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Re: CASE in ORDER BY clause

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Uwe C. Schroeder wrote:

On Saturday 07 July 2007, Lew wrote:

So if your RDBMS sorts NULLs after all other values, then from

select start_date from show_date
order by
  case when start_date > CURRENT_DATE then start_date end desc,
  case when start_date <= CURRENT_DATE then start_date end asc;
all rows with start_date > CURRENT_DATE will appear first, in start_date
descending order,
then all rows with start_date <= CURRENT_DATE will appear, in start_date
ascending order.

Is CURRENT_DATE evaluated once for the query or twice for each row?

CURRENT_DATE is evaluated once per transaction. If you run in autocommit - mode, then the single query is wrapped in a transaction by itself.
Either way it's never evaluated per occurrence.


I'm coming in late on this but you might try something like...

select ... from (
select
...
case when start_date > current date
    then 1 || start_date - current_date
    else 0 || current_date - start_date end "FOO"
)
order by FOO desc

Or something like that...


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