Reuse temporary calculation results in an SQL update query

Поиск
Список
Период
Сортировка
Hello,

is there any way how one can store the result of a time-consuming calculation if this result is needed more than once
inan SQL update query? This solution might be PostgreSQL specific and not standard SQL compliant. Here is an example of
whatI want:
 

UPDATE table1 SET  StartTime = 'time consuming calculation 1',  StopTime = 'time consuming calculation 2',  Duration =
'timeconsuming calculation 2' - 'time consuming calculation 1'
 
WHERE foo;

It would be nice, if I could use the "new" start and stop time to calculate the duration time. First of all it would
makethe SQL statement faster and secondly much more cleaner and easily to understand.
 

Best regards, Matthias

----------------------------------------------------------------------
Matthias Nagel
Willy-Andreas-Allee 1, Zimmer 506
76131 Karlsruhe

Telefon: +49-721-8695-1506
Mobil: +49-151-15998774
e-Mail: matthias.h.nagel@gmail.com
ICQ: 499797758
Skype: nagmat84




В списке pgsql-sql по дате отправления:

Предыдущее
От: "Abhijit Prusty -X (abprusty - UST Global at Cisco)"
Дата:
Сообщение: HOw to convert unicode to string
Следующее
От: Andreas Kretschmer
Дата:
Сообщение: Re: Reuse temporary calculation results in an SQL update query