This is an example:

@strProjectnvarchar(255) = NULL

set nocount on

-- Declarations

...

-- Create Temporary Tables

create table #tblProject

(proj_projectid nvarchar(9) not null primary key)

if ((@strProject IS NULL) OR (@strProject = ''))

insert into #tblProject(proj_projectid)

select prj_code

from Project

else

begin

select...