delimiter

http://www.mysqltutorial.org/getting-started-with-mysql-stored-procedures.aspx

• The first command is DELIMITER // , which is not related to the stored procedure syntax. The DELIMITER statement changes the standard delimiter which is semicolon ( ; ) to another. In this case, the delimiter is changed from the semicolon( ; ) to double-slashes // Why do we have to change the delimiter? Because we want to pass the stored procedure to the server as a whole rather than letting mysql tool interpret each statement at a time.  Following the END keyword, we use the delimiter //  to indicate the end of the stored procedure. The last command ( DELIMITER; ) changes the delimiter back to the semicolon (;).