Original Sproc
	
	CREATE PROC testProc
	as
		SELECT stuff FROM myTable
		WHERE which_stuff = "my stuff"
        go
        
        New Proc (myTable has a historic equivalent)
        
        CREATE PROC testProc_hist
        (
        	@hist_date	datetime
        )
	as
		SELECT stuff FROM myTable_hist
		WHERE  which_stuff = "my stuff"
		AND    hist_date = @hist_date
        go