mysql事务和lock
http://www.cnxct.com/error-1213-40001-deadlock-found-when-trying-to-get-lock-try-restarting-transaction/
http://dev.mysql.com/doc/refman/5.5/en/innodb-lock-modes.html
http://dev.mysql.com/doc/refman/5.0/en/innodb-transaction-model.html
http://blog.csdn.net/zbszhangbosen/article/details/8150761
