case in sql stored procedure on SQL Server

Question

Based on a parameter I'd like to execute a different Update in my stored procedure. I've tried many permutations of the code below, but I always have errors.

    @EmpID int = 0, 
@NewStatus nvarchar(10) = 0
AS
BEGIN
SET NOCOUNT ON;

select CASE   @NewStatus 

when    'InOffice' then 
     Update tblEmployee set InOffice = -1 where EmpID = @EmpID
when   'OutOffice' then 
    Update tblEmployee set InOffice = -1 where EmpID = @EmpID
when 'Home' then 
    Update tblEmployee set Home = -1 where EmpID = @EmpID

END

Answer 1

Try this

If @NewStatus  = 'InOffice' 
BEGIN
     Update tblEmployee set InOffice = -1 where EmpID = @EmpID
END
Else If @NewStatus  = 'OutOffice'
BEGIN
    Update tblEmployee set InOffice = -1 where EmpID = @EmpID
END
Else If @NewStatus  = 'Home'
BEGIN
    Update tblEmployee set Home = -1 where EmpID = @EmpID
END

Answer 2

CASE isn't used for flow control... for this, you would need to use IF...

But, there's a set-based solution to this problem instead of the procedural approach:

UPDATE tblEmployee
SET 
  InOffice = CASE WHEN @NewStatus = 'InOffice' THEN -1 ELSE InOffice END,
  OutOffice = CASE WHEN @NewStatus = 'OutOffice' THEN -1 ELSE OutOffice END,
  Home = CASE WHEN @NewStatus = 'Home' THEN -1 ELSE Home END
WHERE EmpID = @EmpID

Note that the ELSE will preserves the original value if the @NewStatus condition isn't met.