title: Remove duplicate entries from string array column of postgres
body: <p>I have a PostgreSQL table where there is column which has array of strings. The row have some unique array strings or some have duplicate strings also. I want to remove duplicate strings from each row if they exists.</p>
  
  <p>I have tried to some queries but couldn't make it happen.</p>
  
  <p>Following is the table:</p>
  
  <pre><code>  veh_id |             vehicle_types              
   --------+----------------------------------------
        1  | {"byd_tang","volt","viper","laferrari"} 
        2  | {"volt","viper"}                        
        3  | {"byd_tang","sonata","jaguarxf"}        
        4  | {"swift","teslax","mirai"}              
        5  | {"volt","viper"}                        
        6  | {"viper","ferrariff","bmwi8","viper"}   
        7  | {"ferrariff","viper","viper","volt"}    
  </code></pre>
  
  <p>I am expecting following output:</p>
  
  <pre><code>  veh_id |             vehicle_types              
   --------+----------------------------------------
        1  | {"byd_tang","volt","viper","laferrari"} 
        2  | {"volt","viper"}                        
        3  | {"byd_tang","sonata","jaguarxf"}        
        4  | {"swift","teslax","mirai"}              
        5  | {"volt","viper"}                        
        6  | {"viper","ferrariff","bmwi8"}           
        7  | {"ferrariff","viper","volt"}            
  </code></pre>