title: php Random string generation with letters and numbers
body: <p>How to generate a 10 characters random string in PHP including both capital letters and numbers which will never be duplicated or has the least chance of getting duplicated? For example: 34KJ2SCFPS</p>
  
  <p>If I consider only digits, then can <code>$randon = time();</code> be ever duplicated? As time changes every millisecond I don't this its possible. Still, any chance? </p>