Case, If/else Sql Server

Create PROC ReportRequiredBatch
@Plan varchar(5)=null,
@ID varchar(5)=null,
@UserID int

AS

if PlanID= '0' or @Plan IS NULL or @Plan='-1' SET @Plan= ''
if @ID='0' or @ID IS NULL or @ID='-1' SET @ID= ' '


SELECT DISTINCT ICCode, HistoryCode, PlanID, UserID from PlanTable



Could I have done the upper given approach the following way:

CREATE PRoc ReportRequiredBatch
Select Distinct ICCode, HictoryCode, PlanIDCode Case PlanID When '0' or 'null or '-1' Then ' ',
case ID when '0' or 'null or '-1' Then ' ' '


My query might be not exact , free or error. but u get the idea.
What I am trying to see if we can complety take out the If/else and just work on the case.
So is it doable??

For example, in C# or visual basic
we can use if/else and also the select or case. so is it the samething.
or is it better to work with one rather than other.