SQL Server output parameter issue

Question

I am using SQL Server 2008 Enterprise. I am learning OUTPUT parameter of SQL Server stored procedure. For example, stored procedure sp_add_jobschedule has an OUTPUT paramete

Answer 1

One additional note regarding part of the original question:

"Is it allowed not to provide any INPUT values for OUTPUT parameter (..)?"

In SQLServer it is possible to specify a default value for an OUTPUT parameter (which as others have pointed out actually INOUT). Consider the following example in which you could specify a explicit value or let the function itself generate an ID.

CREATE PROCEDURE test (@id uniqueidentifier = NULL OUTPUT) AS
BEGIN
  IF @id IS NULL SET @id = NEWID()
  -- INSERT INTO xyz (...) VALUES (@id, ...)
  PRINT 'Insert with id: ' + CAST (@id as nvarchar(36))
END
GO

DECLARE @insertedId uniqueidentifier
EXECUTE test '00000000-0000-0000-0000-000000000000'
EXECUTE test @insertedId OUTPUT
PRINT @insertedId

DROP PROCEDURE test

This prints

Insert with id: 00000000-0000-0000-0000-000000000000
Insert with id: 67AE3D27-8EAB-4301-B384-30EEA1488440
67AE3D27-8EAB-4301-B384-30EEA1488440