title: How to add HIDDEN property on column?
body: <p>When temporal table is created, we need to defined start and end date time columns 
  which can be <code>hidden</code> - not visible in <code>SELECT *</code> or <code>INSERT without columns</code>. I want to add one more column, which will contain information about the user who has commit the change.</p>
  
  <p>The issue is, I am getting the following error:</p>
  
  <pre><code>Msg 13735, Level 16, State 1, Line 10
  Cannot alter HIDDEN attribute on column 'UserID' in table 'GK' because this column is not a generated always column.
  </code></pre>
  
  <p>Here is the code:</p>
  
  <pre><code>DROP TABLE IF EXISTS GK;
  
  CREATE TABLE GK
  (
      [ID] INT
     ,[UserID] BIGINT DEFAULT (CONVERT(BIGINT, SESSION_CONTEXT(N'user_id')))  
  )
  
  ALTER TABLE GK
  ALTER COLUMN [UserID] ADD HIDDEN;
  </code></pre>
  
  <p>Why I am not allowed to add this attribute on such column?</p>