Most database engines support a couple of SQL functions that help in cases like this, read your database docs for either the ISNULL or the COALESCE function.
Another technique is to use an SQL CASE statement. For all three methods the idea is to supply a default value to substitute when the value in question is NULL. In your case that substituted value would be the value of the 'f_date' column, so in essence the logic would be "use the value of 's_date' if it's NOT NULL, otherwise use the value of 'f_date'". SA has constructs for both the SQL function method and the CASE statemen method; all are documented (well, I think the CASE is....) Rick On 11/8/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > a table, say like this: > name f_date s_dtae > ------------------------------------------------ > name1 2007-10-01 null > name2 2007-06-03 2007-10-07 > name3 2007-09-20 null > name4 ... ... > > the 'f_date' column always contains a value but the 's_date' can > sometimes be null. > now I want to get a collection -- all items will be in it and if the > 's_date' is not null it must > be ordered with 'f_date' of those the 's_date' is null. Just like > this: > > name f_date s_date > ----------------------------------------------- > name3 2007-09-20 null > name1 2007-10-01 null > name2 2007-06-03 2007-10-07 > > any idea? use "select" query....maybe with 'UNION'? > thanks in advance! > > artman > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
