title: SQL Server output parameter issue
body: <p>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 parameter called schedule_id.</p>
  
  <p><a href="http://msdn.microsoft.com/en-us/library/ms366342.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/ms366342.aspx</a></p>
  
  <p>My confusion is, looks like OUTPUT parameter could be provided an input value and also returns a value, looks like it has behaviors of both INPUT and OUTPUT parameter? Is it allowed not to provide any INPUT values for OUTPUT parameter (to make it look like pure output parameter behavior)?</p>