Mysql一个熟悉的概念，一个全新的知识领域。开始我全方位数据库学习之旅。
一切，从安装开始，自己动手每一步。
Linux在安装的过程中，可以勾选Mysql的安装，但是安装的版本是Mysql-5.1.73，版本非常低。必须重新安装，当前最新版本是5.7。但是卸载再安装，明显比空白Linux安装麻烦一点。
下面开始卸载/安装过程。
1. Mysql下载地址
mysql-5.7.22-1.el6.x86_64.rpm-bundle.tar https://dev.mysql.com/downloads/file/?id=4768842. 确认OS版本
# more /etc/issue CentOS release 6.7 (Final) Kernel \r on an \m# lsb_release -a LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch Distributor ID: CentOS Description: CentOS release 6.7 (Final) Release: 6.7 Codename: Final3. 根据OS版本，找到需要下载的Mysql版本，右键“将链接另存为”，即可获得下载地址
4. 到Linux下，通过wget下载
wget https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-community-server-5.7.18-1.el6.x86_64.rpm下面三个rpm包存在依赖关系，也需要下载
# wget https://cdn.mysql.com//Downloads/MySQL-5.7/mysql-community-common-5.7.18-1.el6.x86_64.rpm # wget https://cdn.mysql.com//Downloads/MySQL-5.7/mysql-community-client-5.7.18-1.el6.x86_64.rpm # wget https://cdn.mysql.com//Downloads/MySQL-5.7/mysql-community-libs-5.7.18-1.el6.x86_64.rpm5. 检查查询发现，已经安装Mysql-5.1.73，版本非常低。必须重新安装，当前最新版本是5.7
# rpm -qa | grep mysql mysql-server-5.1.73-5.el6_6.x86_64 mysql-libs-5.1.73-5.el6_6.x86_64 mysql-5.1.73-5.el6_6.x86_64 mysql-connector-odbc-5.1.5r1144-7.el6.x86_646. 准备安装，安装前，就怀疑，会不会覆盖？会不会冲突？安装一下试试，就知道了。
同时安装4个rpm包
# rpm -ivh mysql-community-server-5.7.18-1.el6.x86_64.rpm mysql-community-client-5.7.18-1.el6.x86_64.rpm mysql-community-common-5.7.18-1.el6.x86_64.rpm mysql-community-libs-5.7.18-1.el6.x86_64.rpm7. 果然冲突了
warning: mysql-community-server-5.7.18-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY Preparing... ########################################### [100%] file /usr/share/mysql/czech/errmsg.sys from install of mysql-community-common-5.7.18-1.el6.x86_64 conflicts with file from package mysql-libs-5.1.73-5.el6_6.x86_64 file /usr/share/mysql/danish/errmsg.sys from install of mysql-community-common-5.7.18-1.el6.x86_64 conflicts with file from package mysql-libs-5.1.73-5.el6_6.x86_64 file /usr/share/mysql/dutch/errmsg.sys from install of mysql-community-common-5.7.18-1.el6.x86_64 conflicts with file from package mysql-libs-5.1.73-5.el6_6.x86_64 file /usr/share/mysql/english/errmsg.sys from install of mysql-community-common-5.7.18-1.el6.x86_64 conflicts with file from package mysql-libs-5.1.73-5.el6_6.x86_64 file /usr/share/mysql/estonian/errmsg.sys from install of mysql-community-common-5.7.18-1.el6.x86_64 conflicts with file from package mysql-libs-5.1.73-5.el6_6.x86_64 ......8. 经过查询，也安装失败了，还是5.1.73版本
# rpm -qa|grep mysql mysql-server-5.1.73-5.el6_6.x86_64 mysql-libs-5.1.73-5.el6_6.x86_64 mysql-5.1.73-5.el6_6.x86_64 mysql-connector-odbc-5.1.5r1144-7.el6.x86_649. 开始卸载原有的5.1.73的Mysql，几种卸载方式，首推YUM方式卸载
# yum remove mysql # rpm -e mysql // 普通删除模式 # rpm -e --nodeps mysql // 强力删除模式，如果使用上面命令删除时，提示有依赖的其它文件，则用该命令可以对其进行强力删除10 .还剩余下面两个包
# rpm -qa|grep mysql mysql-libs-5.1.73-5.el6_6.x86_64 mysql-connector-odbc-5.1.5r1144-7.el6.x86_6411. 执行yum localinstall安装，发现需要卸载mysql-libs-5.1.73-5.el6_6.x86_64，通过yun卸载这个包后，可以安装了。
# yum localinstall mysql-community-server-5.7.18-1.el6.x86_64.rpm mysql-community-client-5.7.18-1.el6.x86_64.rpm mysql-community-common-5.7.18-1.el6.x86_64.rpm mysql-community-libs-5.7.18- 1.el6.x86_64.rpm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Loaded plugins: fastestmirror, refresh-packagekit, security Setting up Local Package Process Examining mysql-community-server-5.7.18-1.el6.x86_64.rpm: mysql-community-server-5.7.18-1.el6.x86_64 Marking mysql-community-server-5.7.18-1.el6.x86_64.rpm to be installed Loading mirror speeds from cached hostfile * base: mirrors.163.com * extras: mirrors.cn99.com * updates: mirrors.163.com Examining mysql-community-client-5.7.18-1.el6.x86_64.rpm: mysql-community-client-5.7.18-1.el6.x86_64 Marking mysql-community-client-5.7.18-1.el6.x86_64.rpm to be installed Examining mysql-community-common-5.7.18-1.el6.x86_64.rpm: mysql-community-common-5.7.18-1.el6.x86_64 Marking mysql-community-common-5.7.18-1.el6.x86_64.rpm to be installed Examining mysql-community-libs-5.7.18-1.el6.x86_64.rpm: mysql-community-libs-5.7.18-1.el6.x86_64 Marking mysql-community-libs-5.7.18-1.el6.x86_64.rpm to be installed Resolving Dependencies --> Running transaction check ---> Package mysql-community-client.x86_64 0:5.7.18-1.el6 will be installed ---> Package mysql-community-common.x86_64 0:5.7.18-1.el6 will be installed ---> Package mysql-community-libs.x86_64 0:5.7.18-1.el6 will be installed ---> Package mysql-community-server.x86_64 0:5.7.18-1.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================================================================== Package Arch Version Repository Size ================================================================================================================================== Installing: mysql-community-client x86_64 5.7.18-1.el6 /mysql-community-client-5.7.18-1.el6.x86_64 100 M mysql-community-common x86_64 5.7.18-1.el6 /mysql-community-common-5.7.18-1.el6.x86_64 2.5 M mysql-community-libs x86_64 5.7.18-1.el6 /mysql-community-libs-5.7.18-1.el6.x86_64 8.9 M mysql-community-server x86_64 5.7.18-1.el6 /mysql-community-server-5.7.18-1.el6.x86_64 769 M Transaction Summary ================================================================================================================================== Install 4 Package(s) Total size: 880 M Installed size: 880 M Is this ok [y/N]: y Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : mysql-community-common-5.7.18-1.el6.x86_64 1/4 Installing : mysql-community-libs-5.7.18-1.el6.x86_64 2/4 Installing : mysql-community-client-5.7.18-1.el6.x86_64 3/4 Installing : mysql-community-server-5.7.18-1.el6.x86_64 4/4 Verifying : mysql-community-server-5.7.18-1.el6.x86_64 1/4 Verifying : mysql-community-libs-5.7.18-1.el6.x86_64 2/4 Verifying : mysql-community-common-5.7.18-1.el6.x86_64 3/4 Verifying : mysql-community-client-5.7.18-1.el6.x86_64 4/4 Installed: mysql-community-client.x86_64 0:5.7.18-1.el6 mysql-community-common.x86_64 0:5.7.18-1.el6 mysql-community-libs.x86_64 0:5.7.18-1.el6 mysql-community-server.x86_64 0:5.7.18-1.el6 Complete!12. 最后检查，已经安装成功
# rpm -qa|grep mysql mysql-community-client-5.7.18-1.el6.x86_64 mysql-community-libs-5.7.18-1.el6.x86_64 mysql-community-common-5.7.18-1.el6.x86_64 mysql-community-server-5.7.18-1.el6.x86_6413. 安装完成，但是启动的时候遇到了问题：
# service mysqld restart Stopping mysqld: [ OK ] Initializing MySQL database: 2017-07-11T15:23:50.462866Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2017-07-11T15:23:50.465315Z 0 [ERROR] --initialize specified but the data directory has files in it. Aborting. 2017-07-11T15:23:50.465365Z 0 [ERROR] Aborting [FAILED]14. 百度的解决方法（是由于之前老版本的数据库已经占用这个文件夹，需要清空，或者在/etc/my.cnf中重新指定--datadir）
保证 --datadir目录为空。 /usr/local/var/mysql 这个目录
15. 启动成功
# cd /var/lib/mysql # ls auto.cnf ib_buffer_pool ibdata1 ib_logfile0 ib_logfile1 # rm * rm: remove regular file `auto.cnf'? y rm: remove regular file `ib_buffer_pool'? y rm: remove regular file `ibdata1'? y rm: remove regular file `ib_logfile0'? y rm: remove regular file `ib_logfile1'? y# service mysqld restart
Stopping mysqld: [ OK ] Initializing MySQL database: [ OK ] Installing validate password plugin: [ OK ] Starting mysqld: [ OK ]# ps -ef|grep mysql
root 4533 1 0 23:25 pts/0 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/mysql.sock --pid-file=/var/run/mysqld/mysqld.pid --basedir=/usr --user=mysql mysql 4727 4533 4 23:25 pts/0 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock root 4762 3752 0 23:25 pts/0 00:00:00 grep mysql16. 然而启动的过程中，又遇到一些问题，密码不知道了，重置密码
# mysql -u root ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) [root@test mysql]# mysql -u root -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)编辑mysql配置文件/etc/my.cnf，在[mysqld]这个条目下加入 skip-grant-tables 保存退出后重启mysql
# vi /etc/my.cnf
[root@test mysql]# service mysqld restart Stopping mysqld: [ OK ] Starting mysqld: [ OK ]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 4 Server version: 5.7.18 MySQL Community Server (GPL) Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | +--------------------+ 4 rows in set (0.00 sec)设置密码，然后删除/etc/my.cnf中的 skip-grant-tables
再次重启mysql
mysql> use mysql; Database changed--.给root用户设置新密码：
5.7版本之前：
mysql> update user set password=password("新密码") where user="root"; Query OK, 1 rows affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0在5.7版本之后，mysql数据库下已经没有password这个字段了，password字段改成了authentication_string。
update mysql.user set authentication_string=PASSWORD('oracle') where User='root';mysql> flush privileges; Query OK, 0 rows affected (0.00 sec)---退出mysql，重启然后重新登录
# service mysqld restart Stopping mysqld: [ OK ] Starting mysqld: [ OK ]# mysql -uroot -poracle
mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 5 Server version: 5.7.18 Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>另外有需要云服务器可以了解下创新互联cdcxhl.cn，海内外云服务器15元起步，三天无理由+7*72小时售后在线，公司持有idc许可证，提供“云服务器、裸金属服务器、高防服务器、香港服务器、美国服务器、虚拟主机、免备案服务器”等云主机租用服务以及企业上云的综合解决方案，具有“安全稳定、简单易用、服务可用性高、性价比高”等特点与优势，专为企业上云打造定制，能够满足用户丰富、多元化的应用场景需求。