title: Comparing 2 columns in same database table
body: <p>I have a column in a database table called "ChangePolicy" it always holds a number, and it represents the number of months.  I also have a column in the same table called "LastChanged" and represents the date the item was last changed.  I'm struggling with the query needed to return all items that are due to be changed based on the LastChanged date and the ChangePolicy.  Meaning: If the ChangePolicy is 3 months, I need to return all items that are 3 months or longer since the LastChanged date.</p>
  
  <p>I have the following but it's not providing the desired results.</p>
  
  <pre><code>SELECT * FROM table
  WHERE lastchanged &lt;= dateadd(month, +3, getdate())
  </code></pre>