Select Code to Download

     id        int      NOT NULL auto_increment,
     useragent char(32) NOT NULL,
...
     date      char(32) NOT NULL,
     useragent char(32),              -- added field for ua
     primary key  (id)

     ...
     countdown  int  default(0),
     ...

    UPDATE Table set countdown = countdown + 1 where useragent = ?;

    DELETE FROM Table WHERE countdown > 10;