mysql 怎么启用InnoDB引擎

mysql 如何启用InnoDB引擎？
如题：
mysql> show engines;
+------------+----------+----------------------------------------------------------------+
| Engine     | Support  | Comment                                                        |
+------------+----------+----------------------------------------------------------------+
| MyISAM     | DEFAULT  | Default engine as of MySQL 3.23 with great performance         | 
| MEMORY     | YES      | Hash based, stored in memory, useful for temporary tables      | 
| InnoDB     | DISABLED | Supports transactions, row-level locking, and foreign keys     | 
| BerkeleyDB | YES      | Supports transactions and page-level locking                   | 
| BLACKHOLE  | NO       | /dev/null storage engine (anything you write to it disappears) | 
| EXAMPLE    | NO       | Example storage engine                                         | 
| ARCHIVE    | NO       | Archive storage engine                                         | 
| CSV        | NO       | CSV storage engine                                             | 
| ndbcluster | NO       | Clustered, fault-tolerant, memory-based tables                 | 
| FEDERATED  | NO       | Federated MySQL storage engine                                 | 
| MRG_MYISAM | YES      | Collection of identical MyISAM tables                          | 
| ISAM       | NO       | Obsolete storage engine                                        | 
+------------+----------+----------------------------------------------------------------+

------解决思路----------------------
InnoDB: If this error appears when you are creating an InnoDB database,
InnoDB: the problem may be that during an earlier attempt you managed
InnoDB: to create the InnoDB data files, but log file creation failed.

检查一下你的目录中
ibdata1
ib_logfile0
ib_logfile1

这些文件情况，不行就把这三个文件删除（先备份一下）