title: Delete duplicated string in mysql
body: <p>So i have this result row from a query with GROUP_CONCAT: </p>
  
  <p>clients, employees, employees, providers, providers</p>
  
  <p>And i wanna get something like this:</p>
  
  <p>clients, employees, providers</p>
  
  <p>Please, i'm new here and i need your help, be pacient if the question is not well formed</p>