Where clause and Case Statement

CREATE PROCEDURE [dbo].[Developer_Set]
(
	@ID INT,
        @UserID INT,	
	@EffectiveDate DATETIME,
	@EndDate DATETIME = NULL,
	@UserName VARCHAR(255)
)
AS
BEGIN
	
	SET NOCOUNT ON;

	--Mark previous data as old
	UPDATE Developer
	SET DeletionIndicator = 1
	WHERE ID = @ID AND UserID = @UserID
	
	--Insert New Detail
	INSERT INTO dbo.Developer
	        ( ID ,
	          UserID ,
	          EffectiveDate ,
	          EndDate ,	         
	          DeletionIndicator
	        )
	VALUES  ( @ID , -- 
	          @UserID , -- UserID - int
	          @EffectiveDate, -- EffectiveDate - datetime
	          @EndDate, -- EndDate - datetime	          		 
	          CASE WHEN @EndDate IS NULL THEN 0 ELSE 1 END --DeletionIndicator
	        )

	
END

GO

INSERT INTO dbo.Developer
            ( ID ,
              UserID ,
              EffectiveDate ,
              EndDate ,
              DeletionIndicator
            )
    VALUES  ( @ID , --
              @UserID , -- UserID - int
              @EffectiveDate, -- EffectiveDate - datetime
              @EndDate, -- EndDate - datetime
              CASE WHEN @EndDate IS NULL THEN 0 ELSE 1 END --DeletionIndicator
            ) Where ID= @ID