问题一 Table xx is marked as crashed and last (automatic?) repair failed

有开发找到我，说数据库坏了，连不上数据库，看了下 MySQL 的错误日志，报错如下：

Error: Table './db_name/table_name' is marked as crashed and last (automatic?) repair failed

修复

1、先停止 MySQL：service mysqld stop
2、进入到 MySQL 数据库的文件存放目录，比如 cd /data/mysql_data/xx_db
然后执行如下命令：

myisamchk --safe-recover -f -r *.MYI

执行完成后，为了保险起见，我们要将文件的权限改回 MySQL 的运行账号(自行查看)，比如 mysql：

chown -R mysql:mysql .

3、启动 MySQL：service mysqld start
4、最后，执行再次自动修复优化命令即可解决：

mysqlcheck --auto-repair --optimize --all-databases -p密码

问题二 /usr/local/mysql/bin/mysqld does not exist or is not executable.

]# /data/wapage/hhzk/mserver/mysql5713/bin/mysqld_safe  --defaults-file=/etc/my.cnf &
[1] 24527
]# 2020-11-23T10:36:45.803151Z mysqld_safe Logging to '/data/wapage/hhzk/mserver/mysql5713/data/qd01-tech2-rec-build001.ps.easou.com.err'.
2020-11-23T10:36:45.809116Z mysqld_safe The file /usr/local/mysql/bin/mysqld
does not exist or is not executable. Please cd to the mysql installation
directory and restart this script from there as follows:
./bin/mysqld_safe&
See http://dev.mysql.com/doc/mysql/en/mysqld-safe.html for more information

[1]+  Exit 1                  /data/wapage/hhzk/mserver/mysql5713/bin/mysqld_safe --defaults-file=/etc/my.cnf

说明：mysqld_safe启动脚本默认的从/usr/local/mysql目录中读取另外一个启动脚本mysqld，因为我的安装目录为/data/wapage/hhzk/mserver/mysql5713。所以找不到相关文件。可以从两个方面解决。
方法一：在/usr/local/mysql创建链接文件

mkdir -p /usr/local/mysql/bin
ln -s /data/wapage/hhzk/mserver/mysql5713/bin/mysqld /usr/local/mysql/bin/mysqld

方法二：将mysqld_safe中的所有/usr/local/mysql目录改为自己实际的安装目录

sed -i 's#/usr/local/mysql#/data/wapage/hhzk/mserver/mysql5713#g'  /data/wapage/hhzk/mserver/mysql5713/bin/mysqld_safe