打开mysql日志发下如下错误日志：
2018-01-17 15:55:50 4988 [Note] Plugin 'FEDERATED' is disabled.
2018-01-17 15:55:50 4988 [Note] InnoDB: The InnoDB memory heap is disabled
2018-01-17 15:55:50 4988 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
2018-01-17 15:55:50 4988 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-01-17 15:55:50 4988 [Note] InnoDB: Not using CPU crc32 instructions
2018-01-17 15:55:50 4988 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-01-17 15:55:50 4988 [Note] InnoDB: Completed initialization of buffer pool
2018-01-17 15:55:50 4988 [Note] InnoDB: Highest supported file format is Barracuda.
2018-01-17 15:55:50 4988 [Note] InnoDB: The log sequence numbers 1603124 and 1603124 in ibdata files do not match the log sequence number 1603134 in the ib_logfiles!
2018-01-17 15:55:50 4988 [Note] InnoDB: Database was not shutdown normally!
2018-01-17 15:55:50 4988 [Note] InnoDB: Starting crash recovery.
2018-01-17 15:55:50 4988 [Note] InnoDB: Reading tablespace information from the .ibd files...
2018-01-17 15:55:50 4988 [ERROR] InnoDB: Attempted to open a previously opened tablespace. Previous tablespace hmail/cache uses space ID: 42 at filepath: .hmailcache.ibd. Cannot open tablespace mail/cache which uses space ID: 42 at filepath: .mailcache.ibd
2018-01-17 15:55:50 1480 InnoDB: Operating system error number 997 in a file operation.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/operating-system-error-codes.html
InnoDB: Error: could not open single-table tablespace file .mailcache.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.
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到wamp的mysql的安装目录：D:wampinmysqlmysql5.6.12data
将文件夹下的两个文件ib_logfile0 和 ib_logfile1 改名或者删除，再次启动mysql服务，服务正常启动。系统会自动再重新生成这两个文件。
