I'm tasked with finding a method for Updating a field that is defined as Date in SQL, but rendered as DateTime through BCS (as there is no Date-only type). On the Update form, I only want a Date Picker, not Date AND Time. Can this be done with a custom field type?
I asked this a while ago, but couldn't find any adequate way of doing it. I don't think that External Lists are exactly the same as a normal list, so I'm not convinced that a custom field type would work - but I don't think this was an idea that I'd tried. I also didn't try Infopath (mostly 'cos I hate InfoPath)
I dont think its possible:
Taken from the link above explains well from scott:
This is a question that is asked alot but has no real answer to it except for workarounds!
Hope this helps :)