mysql出现的错误

如果mysql用不了先去管理服务下查看一下是否有mysql
如果没有就要去卸载一下当前已经安装的mysql在此过程中会出现2003错误
你需要将所有的mysql文件卸载干净不然会出现一下错误：
安装到第三步出现红叉
解决步骤如下：

1. 卸载已经安装的mysql
   控制面板–>程序卸载–>找到mysql–>右键卸载

2. 删除注册表所有关于MySQL的项目
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services 下的键值，如果有相关mysql键值(mysql、mysqladmin)删掉
   HKEY_LOCAL_MACHINE/SYSTEM/ControlSet001/Services/Eventlog/Applications/MySQL
   HKEY_LOCAL_MACHINE/SYSTEM/ControlSet002/Services/Eventlog/Applications/MySQL
   HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Eventlog/Applications/MySQL

3. 删除下面目录中所有mysql的有关目录：空目录也要删除
   C:\Program Files (x86)\MySQL
   C:\ProgramData\MySQL

4.关机重启，重新安装
重新安装mysql，安装后先不要运行Server Instance Configuration wizard，重启后在开始菜单中运行该向导，即可。
或者打开安装目录找到MySQLInstanceConfig.exe运行进入配置向导

如果这个完成后没有问题就可以了

如果出现最后一步出现一下问题：
The security settings could not
be applied to the database because the connection has failed with the following
error.
Error Nr. 1045
Access denied for user 'root'@'localhost'
(using password: NO)
If a personal firewall is running on your machine,
please make sure you have opened the TCP port 3306 for connections. Otherwise no
client application can connect to the server. After you have opened the port
please press [Retry] to apply the security settings.
If you are re-installing
after you just uninstalled the MySQL server please note that the data directory
was not removed automatically. Therefore the old password from your last
installation is still needed to connect to the server. In this case please
select skip now and re-run the Configuration Wizard from the start
menu.

解决方法：
1, 控制面板卸载MySQL
2, 删除目录 C:\Documents and Settings\All
Users\Application Data\MySQL
3.只有彻底删除上次install
information之后才能安装，为确保起见，去搜索其他的mysql内容，你也有可能在别的地方安装过mysql的。
3, 重新安装MySQL
就好了
如何你C:\Documents and Settings\All Users下没有Application
Data文件夹，选择：工具——文件夹选项——查看——选择显示所有文件和文件夹。