Inkrementerande datetime-fält med en uppdateringssats

Du kan använda sessionsvariabler:

SET @r := -1;

UPDATE  mytable
SET     mydate = mydate + INTERVAL (@r := @r + 1) DAY;

I SQL Server 2005 :

WITH    q AS
        (
        SELECT  *,
                ROW_NUMBER() OVER (ORDER BY mydate) rn
        FROM    mytable
        )
UPDATE  q
SET     mydate = DATEADD(d, rn - 1, mydate)