>>>Hi,
>>>
>>>When setting up table unique constraint I wanted to have a column value as part of the expression but don't seem to see how to do it in SSMS. For example, say I want the constraint to be on column MyColumn1 plus MyColumn2='1'. Can this be done?
>>>
>>>TIA.
>>
>>There doesn't seem to be a way to do this in the design view. You need to do this in code - specify unique constraint on both columns.
>
>I will try the approach of Check constraint as Sergey suggested. Thank you.

If you want some calculations like you described, then you need to use a Check constraint. Check constraint you can design visually.