>>I am doing an INSERT INTO from a SELECT. In the SELECT list of fields, I need to apply a condition to either use one field or another. What would be the syntax to support that?
>
>Maybe CASE in the select?

Right, yes, you can use a CASE

insert into MyTable  (Column1, Column2, Column3 )
   select    case when SomeColumn = 'Use Column1a' then Column1a else Column1b end as Column1,   Column2, Column3 From SomeOtherTable