title: How to check if Datarow value is null
body: <p>Tell me please is this is correct way to check NULL in DataRow if need to return a <code>string</code></p>
  
  <pre><code> Convert.ToString(row["Int64_id"] ?? "")
  </code></pre>
  
  <p>Or should be like check with DBNull.Value.</p>
  
  <p>Need to so much more smaller than </p>
  
  <pre><code>if(row["Int64_id"] != DBNull.Value){...}else if{}
  </code></pre>