title: How to define that an attribute is optional?
body: <p>I'm programming with SQL Server 2014 Management Studio.</p>
  
  <p>I want to build in my program an optional attribute.</p>
  
  <p>E.g </p>
  
  <pre><code>CREATE TABLE [Picture]
  (
      Title VARCHAR(20),
      Signature VARCHAR(20),    &lt;--- should be optional
      Alttext VARCHAR(20)
  )
  </code></pre>