Seperate Date And Time Merge; Done At SQL Update Or C# .NET Then Update

I do realize that his could be posted in a few spots but I think the answer is in the SQL.

I have a ASP.NET page, with a SqlDataSource, Text Box and Calendar Controls. I have the textbox and calendar controls eval'ed to the same sql data source DateTime Field. The text box is formatted eval to small time and the calendars eval has no formatting.

ex:

<asp:TextBox ID="START_TIME" Text='<%# Eval("EVENT_START","{0:t}") %>' runat=server Width=200></asp:TextBox>

I want to merge the two controls; one has the date the other has the time when I update the pages data to the SqlDataSource field EVENT_START. I've tried a couple of methods, but I would like some other opinions. As Sql server only supports date and time together I am storing the two together.

I could merge the two together in the code behind on the update button's event handler or merge the two during the update query using parameters.

Not that I could get an illegal date for the calendar control, but I could get garbage from the textfield time. So I still would have to do validation on the text field before the SQL server could do the update.

There's a few ways to go about this, so I was wondering if anyone else has figured out an elegant way to handle it.

wbochar