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
