title: In SQL Server, what does "SET ANSI_NULLS ON" mean?
body: <p>The definition says:</p>
  
  <blockquote>
    <p>When SET ANSI_NULLS is ON, a SELECT statement that uses WHERE column_name = NULL returns zero rows even if there are null values in column_name. A SELECT statement that uses WHERE column_name &lt;> NULL returns zero rows even if there are non-null values in column_name.</p>
  </blockquote>
  
  <p>Does this mean that no nulls will be included in this query?</p>
  
  <pre><code>SELECT Region
  FROM employees
  WHERE Region = @region
  </code></pre>
  
  <p>Or do <code>ANSI_NULL</code>s concern only queries like this one (where the <code>WHERE</code> includes the specific word <code>NULL</code>)?</p>
  
  <pre><code>SELECT Region
  FROM employees
  WHERE Region = NULL
  </code></pre>