On Wed, Mar 19, 2008 at 12:13:42AM +0500, Mamkin Mansur wrote: > If I need timestamp (datetime) relation in my DB-class, how can I do > it? I need this for sorting objects by datetime.
The best way is to define a relation in that class which holds a date and a time: (class +MyClass +Entity) ... (rel ts (+Ref +Bag) NIL ((+Date)) ((+Time))) # Timestamp ... Then you could create new objects with a timestamp (new! '(+MyClass) .. 'ts (list (date) (time T)) ..) or put a time stamp on existing objects (put!> ObjOfMyClass 'ts (list (date) (time T))) Note that calling 'time' with an argument 'T' is a new feature of the next release (due to the end of this month). It guarantees atomicity of 'date' followed by 'time'. For example, to find all objects that have a timestamp within a given range (collect 'ts '+MyClass (list (date 2008 3 15) (time 12 30)) (list (date 2008 3 19) (time 17 10)) ) Cheers, Alex -- Software Lab. Alexander Burger Bahnhofstr. 24a, D-86462 Langweid [EMAIL PROTECTED], www.software-lab.de, +49 8230 5060