title: Return value based on duplicate columns
body: <pre><code>Table:    
  firstname  |   lastname   |  age      
  Joey       |   Sanchez    |  33   
  Joey       |   Sanchez    |  33   
  Rachel     |   Dudok      |  28
  </code></pre>
  
  <p>I'm trying to make a MySQL select statement that returns a value "<strong>ERROR</strong>" in the age column when 2 columns are duplicates</p>
  
  <p>I tried the Case statement but it only ends up returning 1 row. </p>
  
  <pre><code> SELECT 
   Firstname,
   Lastname,
   CASE
      WHEN count(firstname) AND count(lastname) AND count(age) &gt;= 2 
       THEN '**ERROR**'
       ELSE age
   END
   FROM Table;
  </code></pre>