Lynn Pettis (5/7/2013)
First, I don't think your question is really about why is the index on the view being selected as much as why the first query generates 5 index seeks while the second only one.
That was what my other question was about 🙂
Lynn Pettis (5/7/2013)
The reason is the first generates 5 index seeks is that SQL Server has to generate a plan that covers all possible execution paths in the first query. The CASE statement is not evaluated during this phase, it is evaluated during the execution of the query itself.
I am surprised that IF ELSE IF statements don't generate similar plans than CASE statements.