How To Get Index Seek

Hi,

Can I use index seek and still keep 'like' 'or' functionality for the following statement?



--prepare test table

create table entity (Id int identity(1,1), FamName varchar(200), LastName varchar(200))
go
create clustered index entity_id on entity (id)
go
create nonclustered index entity_lastName on entity (lastName)
go
insert into entity select famName,FirstName from table

--test index

declare @LastName varchar(10)
set @LastName = 'a'

select FamName
from entity
where @LastName is null or LastName like @LastName --clustered index scan