title: Data validation - Drop down list with no duplicates in excel
body: <p>Could you please assist me  with <strong>removing duplicates</strong> in a <strong>drop down list</strong>. The list is not static. Example:</p>
  
  <p><strong>Before</strong></p>
  
  <pre><code>James
  Peter
  James
  Nick
  Peter
  </code></pre>
  
  <p><strong>After</strong></p>
  
  <pre><code>James
  Peter
  Nick
  </code></pre>
  
  <p>I am not sure what formula to use data validation formula box.</p>
  
  <p>I had attempted the below, but no success:</p>
  
  <pre><code>=OFFSET($C$13,0,0,COUNTIF(C:C,"?*")-1)
  </code></pre>