title: mysql NULL value in where in CLAUSE
body: <p>how to deal with <strong>NULL</strong> value in mysql <strong>where in</strong> CLAUSE</p>
  
  <p>i try like </p>
  
  <pre><code>SELECT * FROM mytable WHERE field IN(1,2,3,NULL)
  </code></pre>
  
  <p>it not working</p>
  
  <p>only work like :</p>
  
  <pre><code>SELECT * FROM mytable WHERE field IN(1,2,3) OR field IS NULL
  </code></pre>
  
  <p>how can i get it work in <code>WHERE IN</code> ?  it is possible ?</p>