title: Extract domain_name alone from email_id in Hive
body: <p>In my Hive table, i have an email address column : xxxx@gmail.com 
  i want to display "gmail" alone. I tried using regexp_extract but not getting the desired output. nowhere near.</p>
  
  <p>Also for email ids like xxxx@ffff.nec.co.jp , i want the output to be "ffff.nec.co" </p>
  
  <p>Below is my expression : select regexp_extract('xxxx@gmail.com','.([^.]+)')
  but it does not bring the desired output. 
  Please help me out guys. Regexp or substr is fine for me. </p>