title: Trigger for checking duplicate email address
body: <p>Is it a good option to write mysql trigger to check duplicate email address.So, that Mysql reject the insertion of duplicate email address.</p>
  
  <p>Or,</p>
  
  <p>It is good to do in application ? i.e  read all email address from user table and then in PHP do the comparison.</p>
  
  <p>I am reading about mysql trigger and I though it would be good option instead of doing in php ..Kindly advice. </p>
  
  <p>Regards,</p>