轉自https://www.cnblogs.com/wsl222000/p/5445768.html

1.安裝mysql-5.5的yum源

rpm -ivh http://repo.mysql.com/yum/mysql-5.5-community/el/6/x86_64/mysql-community-release-el6-5.noarch.rpm

要安裝MySQL5.6的可以安裝：

rpm -ivh http://repo.mysql.com/mysql-community-release-el6.rpm

最新的yum源可以去http://dev.mysql.com/downloads/repo/yum下載

2.修改安裝好的yum源

編輯 /etc/yum.repos.d/mysql-community.repo文件，將5.5的enabled改為1,5.6的enabled改為0

# Enable to use MySQL 5.5
[mysql55-community]
name=MySQL 5.5 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.5-community/el/6/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

# Enable to use MySQL 5.6
[mysql56-community]
name=MySQL 5.6 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.6-community/el/6/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

3.安裝mysql-5.5

 yum install mysql-community-client mysql-community-devel mysql-community-server php-mysql

4.調整配置

編輯 /etc/my.cnf 文件

innodb_file_per_table=1 設置InnoDB為獨立表空間模式，每個數據庫的每個表都會生成一個數據目錄
innodb_buffer_pool_size= 默認值：128M，設置為操作系統內存的70%-80%最佳
service mysqld start   啟動mysql
chkconfig mysqld on    設為開機啟動

mysqladmin -u root password ‘root‘   設置密碼為root

CentOS 6.*通過yum安裝 MySQL-5.5