mysql roll back

START TRANSACTION(或者begin);
  SAVEPOINT point1;
  if  ???? then
    ROLLBACK TO SAVEPOINT point1;

　#(回滚到SAVEPOINT处)
  else
　　.......
  end if;

  COMMIT;(必须,否则会引起Lock wait timeout exceeded; try restarting transaction的错误,并导致所操作的表被死锁)