You can check this out for some ideas:
http://www.codeproject.com/aspnet/MellDataCalendar.asp
The dataset should be created once in the pageload.
The url above, he uses the dataset filter property to find matches with the
day.
...
"Dabbler" <> wrote in message
news:C72C14A1-C8EC-41F1-B86A-...
> I'm trying to customize calendar days using data in a table. Some days may
> have corresponding rows in the table giving counts for that day. I'm not
> clear on when I should get the data from the table so it is available for
> DayRender event.
>
> In some cases the SelectedChanged event causes the calendar to refresh, in
> others it would be a FormView ItemInserted event.
>
> Which event is best to use so the data is present in the DayRender event?
> Obviously I don't want to create the dataset in this event as it would
> trigger 30~ times per postback.
>
> Thanks for any insight.
>
> I need to load a dataset to respond to Calendar DayRender event. I need
this
> data set to be present also for SelectionChanged event and events on a
> FormView ItemInserted etc.
>
> Wh