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。
1、确认mysql是否已安装，有下面的代码可知[root@cdh1 zjl]# yum list installed mysql*Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile * base: mirrors.zju.edu.cn * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com
Installed Packages
MySQL-python.x86_64 1.2.3-0.3.c1.1.el6 @base
mysql-libs.x86_64 5.1.73-8.el6_8 @anaconda-CentOS-201703281317.x86_64/6.9
2、卸载已安装的mysql，建议使用yum命令，因为yum命令可以自动删除与mysql相关的依赖；如果使用rpm命令，则还需要手动去删除和mysql相关的文件，比较麻烦
[root@cdh1 zjl]# yum remove MySQL-python.x86_64 mysql-libs.x86_64
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Remove Process
Resolving Dependencies--> Running transaction check---> Package MySQL-python.x86_64 0:1.2.3-0.3.c1.1.el6 will be erased--> Processing Dependency: MySQL-python for package: cloudera-manager-agent-5.11.1-1.cm5111.p0.9.el6.x86_64---> Package mysql-libs.x86_64 0:5.1.73-8.el6_8 will be erased--> Processing Dependency: libmysqlclient.so.16()(64bit) for package: 2:postfix-2.6.6-8.el6.x86_64--> Processing Dependency: libmysqlclient.so.16(libmysqlclient_16)(64bit) for package: 2:postfix-2.6.6-8.el6.x86_64--> Processing Dependency: mysql-libs for package: 2:postfix-2.6.6-8.el6.x86_64--> Running transaction check---> Package cloudera-manager-agent.x86_64 0:5.11.1-1.cm5111.p0.9.el6 will be erased---> Package postfix.x86_64 2:2.6.6-8.el6 will be erased--> Processing Dependency: /usr/sbin/sendmail for package: redhat-lsb-core-4.0-7.el6.centos.x86_64--> Processing Dependency: /usr/sbin/sendmail for package: cronie-1.4.4-16.el6_8.2.x86_64--> Running transaction check---> Package cronie.x86_64 0:1.4.4-16.el6_8.2 will be erased--> Processing Dependency: cronie = 1.4.4-16.el6_8.2 for package: cronie-anacron-1.4.4-16.el6_8.2.x86_64---> Package redhat-lsb-core.x86_64 0:4.0-7.el6.centos will be erased--> Processing Dependency: redhat-lsb-core(x86-64) = 4.0 for package: redhat-lsb-printing-4.0-7.el6.centos.x86_64--> Processing Dependency: redhat-lsb-core(x86-64) = 4.0-7.el6.centos for package: redhat-lsb-4.0-7.el6.centos.x86_64--> Processing Dependency: redhat-lsb-core(x86-64) = 4.0 for package: redhat-lsb-graphics-4.0-7.el6.centos.x86_64--> Running transaction check---> Package cronie-anacron.x86_64 0:1.4.4-16.el6_8.2 will be erased---> Package redhat-lsb.x86_64 0:4.0-7.el6.centos will be erased--> Processing Dependency: redhat-lsb(x86-64) = 4.0-7.el6.centos for package: redhat-lsb-compat-4.0-7.el6.centos.x86_64---> Package redhat-lsb-graphics.x86_64 0:4.0-7.el6.centos will be erased---> Package redhat-lsb-printing.x86_64 0:4.0-7.el6.centos will be erased--> Running transaction check---> Package redhat-lsb-compat.x86_64 0:4.0-7.el6.centos will be erased--> Processing Dependency: /etc/cron.d for package: crontabs-1.10-33.el6.noarch--> Processing Dependency: /etc/cron.d for package: sysstat-9.0.4-33.el6.x86_64--> Restarting Dependency Resolution with new changes.--> Running transaction check---> Package crontabs.noarch 0:1.10-33.el6 will be erased---> Package sysstat.x86_64 0:9.0.4-33.el6 will be erased--> Finished Dependency Resolution
Dependencies Resolved====================================================================
Package Arch Version Repository
Size====================================================================Removing:
MySQL-python x86_64 1.2.3-0.3.c1.1.el6 @base 246 k
mysql-libs x86_64 5.1.73-8.el6_8 @anaconda-CentOS-201703281317.x86_64/6.9 4.0 M
Removing for dependencies:
cloudera-manager-agent x86_64 5.11.1-1.cm5111.p0.9.el6 @/cloudera-manager-agent-5.11.1-1.cm5111.p0.9.el6.x86_64 71 M
cronie x86_64 1.4.4-16.el6_8.2 @anaconda-CentOS-201703281317.x86_64/6.9 174 k
cronie-anacron x86_64 1.4.4-16.el6_8.2 @anaconda-CentOS-201703281317.x86_64/6.9 43 k
crontabs noarch 1.10-33.el6 @anaconda-CentOS-201703281317.x86_64/6.9 2.4 k
postfix x86_64 2:2.6.6-8.el6 @anaconda-CentOS-201703281317.x86_64/6.9 9.7 M
redhat-lsb x86_64 4.0-7.el6.centos @anaconda-CentOS-201703281317.x86_64/6.9 0.0
redhat-lsb-compat x86_64 4.0-7.el6.centos @anaconda-CentOS-201703281317.x86_64/6.9 0.0
redhat-lsb-core x86_64 4.0-7.el6.centos @anaconda-CentOS-201703281317.x86_64/6.9 22 k
redhat-lsb-graphics x86_64 4.0-7.el6.centos @anaconda-CentOS-201703281317.x86_64/6.9 0.0
redhat-lsb-printing x86_64 4.0-7.el6.centos @anaconda-CentOS-201703281317.x86_64/6.9 0.0
sysstat x86_64 9.0.4-33.el6 @anaconda-CentOS-201703281317.x86_64/6.9 826 k
Transaction Summary====================================================================Remove 13 Package(s)
Installed size: 86 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Erasing : redhat-lsb-compat-4.0-7.el6.centos.x86_64 1/13
Erasing : redhat-lsb-4.0-7.el6.centos.x86_64 2/13
Erasing : cloudera-manager-agent-5.11.1-1.cm5111.p0.9. 3/13 warning: /etc/cloudera-scm-agent/config.ini saved as /etc/cloudera-scm-agent/config.ini.rpmsave
Erasing : redhat-lsb-graphics-4.0-7.el6.centos.x86_64 4/13
Erasing : redhat-lsb-printing-4.0-7.el6.centos.x86_64 5/13
Erasing : redhat-lsb-core-4.0-7.el6.centos.x86_64 6/13 /var/tmp/rpm-tmp.jLbJUk: line 1: lsb_release: command not found
Erasing : MySQL-python-1.2.3-0.3.c1.1.el6.x86_64 7/13
Erasing : sysstat-9.0.4-33.el6.x86_64 8/13
Erasing : crontabs-1.10-33.el6.noarch 9/13
Erasing : cronie-anacron-1.4.4-16.el6_8.2.x86_64 10/13
Erasing : cronie-1.4.4-16.el6_8.2.x86_64 11/13
Erasing : 2:postfix-2.6.6-8.el6.x86_64 12/13
Erasing : mysql-libs-5.1.73-8.el6_8.x86_64 13/13
Verifying : redhat-lsb-printing-4.0-7.el6.centos.x86_64 1/13
Verifying : cronie-anacron-1.4.4-16.el6_8.2.x86_64 2/13
Verifying : cronie-1.4.4-16.el6_8.2.x86_64 3/13
Verifying : 2:postfix-2.6.6-8.el6.x86_64 4/13
Verifying : redhat-lsb-4.0-7.el6.centos.x86_64 5/13
Verifying : redhat-lsb-core-4.0-7.el6.centos.x86_64 6/13
Verifying : cloudera-manager-agent-5.11.1-1.cm5111.p0.9. 7/13
Verifying : crontabs-1.10-33.el6.noarch 8/13
Verifying : redhat-lsb-compat-4.0-7.el6.centos.x86_64 9/13
Verifying : MySQL-python-1.2.3-0.3.c1.1.el6.x86_64 10/13
Verifying : redhat-lsb-graphics-4.0-7.el6.centos.x86_64 11/13
Verifying : sysstat-9.0.4-33.el6.x86_64 12/13
Verifying : mysql-libs-5.1.73-8.el6_8.x86_64 13/13 Removed:
MySQL-python.x86_64 0:1.2.3-0.3.c1.1.el6
mysql-libs.x86_64 0:5.1.73-8.el6_8
Dependency Removed:
cloudera-manager-agent.x86_64 0:5.11.1-1.cm5111.p0.9.el6
cronie.x86_64 0:1.4.4-16.el6_8.2
cronie-anacron.x86_64 0:1.4.4-16.el6_8.2
crontabs.noarch 0:1.10-33.el6
postfix.x86_64 2:2.6.6-8.el6
redhat-lsb.x86_64 0:4.0-7.el6.centos
redhat-lsb-compat.x86_64 0:4.0-7.el6.centos
redhat-lsb-core.x86_64 0:4.0-7.el6.centos
redhat-lsb-graphics.x86_64 0:4.0-7.el6.centos
redhat-lsb-printing.x86_64 0:4.0-7.el6.centos
sysstat.x86_64 0:9.0.4-33.el6
Complete!
[root@cdh1 zjl]# whereis mysql
mysql:
[root@cdh1 zjl]# yum list mysql*Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile * base: mirrors.zju.edu.cn * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com
Available Packages
MySQL-python.x86_64 1.2.3-0.3.c1.1.el6 base
mysql.x86_64 5.1.73-8.el6_8 base
mysql-bench.x86_64 5.1.73-8.el6_8 base
mysql-connector-java.noarch 1:5.1.17-6.el6 base
mysql-connector-odbc.x86_64 5.1.5r1144-7.el6 base
mysql-devel.i686 5.1.73-8.el6_8 base
mysql-devel.x86_64 5.1.73-8.el6_8 base
mysql-embedded.i686 5.1.73-8.el6_8 base
mysql-embedded.x86_64 5.1.73-8.el6_8 base
mysql-embedded-devel.i686 5.1.73-8.el6_8 base
mysql-embedded-devel.x86_64 5.1.73-8.el6_8 base
mysql-libs.i686 5.1.73-8.el6_8 base
mysql-libs.x86_64 5.1.73-8.el6_8 base
mysql-server.x86_64 5.1.73-8.el6_8 base
mysql-test.x86_64 5.1.73-8.el6_8 base
[root@cdh1 zjl]# mysql--***-->---> Package mysql-server.x86_64 :.---> Processing Dependency: mysql = .-.el6_8 package: mysql-server-.---> Processing Dependency: -DBI package: mysql-server-.---> Processing Dependency: -DBD-MySQL package: mysql-server-.---> Processing Dependency: (DBI) package: mysql-server-.---> Processing Dependency: libmysqlclient_r.so.(libmysqlclient_16)(64bit) package: mysql-server-.---> Processing Dependency: libmysqlclient.so.(libmysqlclient_16)(64bit) package: mysql-server-.---> Processing Dependency: libmysqlclient_r.so.()(64bit) package: mysql-server-.---> Processing Dependency: libmysqlclient.so.()(64bit) package: mysql-server-.--->---> Package mysql.x86_64 :.----> Package mysql-libs.x86_64 :.----> Package -DBD-MySQL.x86_64 :----> Package -DBI.x86_64 :--->==================================================================================================================================================================================================================================================================================================================================================================================================================================-server x86_64 .-.el6_8 base .-.el6_8 base -libs x86_64 .-.el6_8 base -DBD-MySQL x86_64 -.el6 base -DBI x86_64 -.el6 base =================================================================================================================================================================================================================/
Is this ok [y/N]: y
Downloading Packages:
(1/5): mysql-5.1.73-8.el6_8.x86_64.rpm