title: Add a column to a table, if it does not already exist
body: <p>I want to write a query for MS SQL Server that adds a column into a table. But I don't want any error display, when I run/execute the following query.</p>
  
  <p>I am using this sort of query to add a table ...</p>
  
  <pre><code>IF EXISTS (
         SELECT *
         FROM   sys.objects
         WHERE  OBJECT_ID = OBJECT_ID(N'[dbo].[Person]')
                AND TYPE IN (N'U')
     )
  </code></pre>
  
  <p>But I don't know how to write this query for a column.</p>