SQL是Structured Query Language(结构化查询语言)的缩写。SQL是专为数据库而建立的操作命令集，是一种功能齐全的数据库语言。在使用它时，只需要发出“做什么”的命令，“怎么做”是不用使用者考虑的。SQL功能强大、简单易学、使用方便，已经成为了数据库操作的基础，并且现在几乎所有的数据库均支持SQL。 这篇文章主要介绍了MySQL无法启动的解决办法的相关资料,希望通过本文大家能解决数据库不能启动的问题，需要的朋友可以参考下MySQL无法启动的解决办法 MySQL无法启动
在停止mysql之后，执行了一些操作（如修改主机名），重新启动 mysql，发现起不来。
[root@www ~]$ service mysql start
Starting MySQL..^[[A.................................................................................................. ERROR! The server quit without updating PID file (/disk/mysql/www.pid).
[root@www ~]$ service mysql stop
ERROR! MySQL server PID file could not be found!
[root@www ~]$ service mysql stop
ERROR! MySQL server PID file could not be found!
[root@www ~]$ service mysql start
Starting MySQL..................
还是老样子，只好 Ctr+C 掉。
[root@www ~]$ 实在是启动不了，看一下日志：/disk/mysql/www.err
120608 09:56:17 mysqld_safe Starting mysqld daemon with databases from /disk/mysql
120608 9:56:17 [Note] Plugin 'FEDERATED' is disabled.
120608 9:56:17 InnoDB: The InnoDB memory heap is disabled
120608 9:56:17 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
120608 9:56:17 InnoDB: Comdivssed tables use zlib 1.2.3
120608 9:56:17 InnoDB: Using Linux native AIO
120608 9:56:17 InnoDB: Initializing buffer pool, size = 128.0M
120608 9:56:17 InnoDB: Completed initialization of buffer pool
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
120608 9:56:17 InnoDB: Retrying to lock the first data file
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
... 好像是原来的 mysqld 并没有停下来。
强制终止 mysqld
[root@www ~]$ ps -ef |