title: PROCEDURE test_multi_sets in mysql
body: <p>can someone explain me what does this chunk of code means?</p>
  
  <pre><code>DELIMITER $$
  --
  -- Procedures
  --
  CREATE DEFINER=`username`@`localhost` PROCEDURE `test_multi_sets`()
      DETERMINISTIC
  begin
          select user() as first_col;
          select user() as first_col, now() as second_col;
          select user() as first_col, now() as second_col, now() as third_col;
          end$$
  
  DELIMITER ;
  </code></pre>
  
  <p>Because my database exports only with this, and it seems to cause troubles for me to import it to another server.</p>