>>>Hi,
>>>
>>Can you clarify your question? Do you want to create UPDATE statement but don't know the structure of the table in advance?
>>
>>Take a lot at INFORMATION_SCHEMA.Columns view to check if the table has column or alternatively into sys.columns.
>
>I have a case where the UPDATE expression has to work on tables that some do have column FieldB and some don't. Using INFORMATION_SCHEMA would not be applicable here. I would like to have th UPDATE expressing itself check if the column exists or not. If this is possible, of course. If not, I will use a different approach.

In SQL Server you need to query some system view to find out if the column exists or not and then create dynamic SQL to execute the query. There is no other magic way.