在安装过程中所遇到的问题有：

1、my-default.cnf文件找不到

2、mysql启动报错

3、mysql临时密码无法登录

安装环境centos 6.0

下载数据库：

[root@CLanguage src]# pwd

/usr/local/src #下载文件存放路径(个人原因，可随意。)

[root@CLanguage src]#

wget https://cdn.mysql.com//Downloads/MySQL-5.7/mysql-5.7.21-linux-glibc2.12-x86_64.tar.gz

[root@CLanguage src]# tar -zxvf mysql-5.7.21-linux-glibc2.12-x86_64.tar.gz #解压

[root@CLanguage src]# mv mysql-5.7.21-linux-glibc2.12-x86_64 mysql

#更改文件名

卸载旧版本：

[root@CLanguage src]# rpm -qa |grep mysql

mysql-5.1.47-4.el6.x86_64

mysql-libs-5.1.47-4.el6.x86_64

mysql-devel-5.1.47-4.el6.x86_64

[root@CLanguage src]# rpm -e --nodeps mysql-5.1.47-4.el6.x86_64

[root@CLanguage src]# rpm -e --nodeps mysql-libs-5.1.47-4.el6.x86_64

[root@CLanguage src]# rpm -e --nodeps mysql-devel-5.1.47-4.el6.x86_64

[root@CLanguage src]# rpm -qa |grep mysql

[root@CLanguage src]#

创建数据库目录以及用户和组：

[root@CLanguage src]#mkdir /data

[root@CLanguage src]#mkdir /data/mysqldata #数据存放目录

[root@CLanguage src]#groupadd mysql #创建mysql组

[root@CLanguage src]#useradd -r -s /sbin/nologin -g mysql mysql -d /usr/local/src/mysql #添加mysql用户使其shell模式为nologin(禁止登录)，

[root@CLanguage mysql]# chown -R mysql .

[root@CLanguage mysql]# chgrp -R mysql .

[root@CLanguage mysql]#chown -R mysql /data/mysqldata

安装前先安装numactl组件，或者会报错：bin/mysqld: error while loading shared libraries: libnuma.so.1

[root@CLanguage mysql]# yum -y install numactl

(可以使用本地CD yum源进行安装，前提是搭建好后。)

配置参数:

[root@CLanguage src]# cd mysql

[root@CLanguage mysql]# bin/mysqld --initialize --user=mysql --basedir=/usr/local/src/mysql --datadir=/data/mysqldata/ #配置参数

2018-01-31T08:41:32.144065Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).

2018-01-31T08:41:34.501273Z 0 [Warning] InnoDB: New log files created, LSN=45790

2018-01-31T08:41:34.943351Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.

2018-01-31T08:41:35.016168Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 8b673fc1-0662-11e8-a70a-000c298536ba.

2018-01-31T08:41:35.021358Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.

2018-01-31T08:41:35.025019Z 1 [Note] A temporary password is generated for root@localhost: dhaMrqAVZ5-C {最后的root@localhost：后面为临时密码}

--basedir=/usr/local/src/mysql #mysql文件所在目录

--datadir=/data/mysqldata/ #数据库存放目录

[root@CLanguage mysql]# bin/mysql_ssl_rsa_setup --datadir=/data/mysqldata/

#配置参数

修改系统配置文件:

在support-files目录未发现my-default.cnf文件,所以只能手动创建了。

[root@CLanguage support-files]# vim /etc/my.cnf (创建my.cnf，将以下代码复制进去，记得下面几个目录需要自己手动修改为自己定义的目录)

[client]

port = 3306

socket = /tmp/mysql.sock

[mysqld]

character_set_server=utf8

init_connect='SET NAMES utf8'

basedir=/usr/local/src/mysql #文件存放目录

datadir=/data/mysqldata/ #数据库存放目录

socket=/tmp/mysql.sock #以上面socket值要一致

log-error=/var/log/mysqld.log

pid-file=/var/run/mysqld/mysqld.pid

lower_case_table_names = 1

sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

max_connections=5000

default-time_zone = '+8:00'

(这里参数不全，可以去其他地方拷贝一个my.cnf文件)

或者拷贝以下内容：

[mysqld]

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES # 一般配置选项

basedir = /usr/local/src/mysql #需修改

datadir = /data/mysqldata #需修改

port = 3306

socket = /var/run/mysqld/mysqld.sock

character-set-server=utf8

back_log = 300

max_connections = 3000

max_connect_errors = 50

table_open_cache = 4096

max_allowed_packet = 32M

#binlog_cache_size = 4M

max_heap_table_size = 128M

read_rnd_buffer_size = 16M

sort_buffer_size = 16M

join_buffer_size = 16M

thread_cache_size = 16

query_cache_size = 128M

query_cache_limit = 4M

ft_min_word_len = 8

thread_stack = 512K

transaction_isolation = REPEATABLE-READ

tmp_table_size = 128M

#log-bin=mysql-bin

long_query_time = 6

server_id=1

innodb_buffer_pool_size = 1G

innodb_thread_concurrency = 16

innodb_log_buffer_size = 16M

innodb_log_file_size = 512M

innodb_log_files_in_group = 3

innodb_max_dirty_pages_pct = 90

innodb_lock_wait_timeout = 120

innodb_file_per_table = on

[mysqldump]

quick

max_allowed_packet = 32M

[mysql]

no-auto-rehash

default-character-set=utf8

safe-updates

[myisamchk]

key_buffer = 16M

sort_buffer_size = 16M

read_buffer = 8M

write_buffer = 8M

[mysqlhotcopy]

interactive-timeout

[mysqld_safe]

open-files-limit = 8192

[root@CLanguage support-files]# cp mysql.server /etc/init.d/mysqld

[root@CLanguage support-files]# vim /etc/init.d/mysqld

修改/etc/init.d/mysqld在basedir和datadir后填入文件存放路径和数据存放路径

启动mysql：

[root@CLanguage mysql]# bin/mysqld_safe --user=mysql & #检测

[root@CLanguage run]# /etc/init.d/mysql start (这里会报错，因为找不到mysqld文件夹，所以要创建并赋予权限。)

[root@CLanguage mysql]# cd /var/run/

[root@CLanguage run]# mkdir mysqld

[root@CLanguage run]# chown -R mysql mysqld

[root@CLanguage run]# chgrp -R mysql mysqld

[root@CLanguage run]# /etc/init.d/mysqld start

Starting MySQL... [ OK ]

登录mysql已经修改密码：

如果使用bin/mysql -uroot -p无法登录时，可以使用以下办法进行密码重设：

修改/etc/my.cnf文件

在[mysqld]下面添加“skip-grant-tables”

(skip-grant-tables命令为跳过验证，直接登录。个人认为好比linux的单用户模式，来进行mysql的密码修改。)

重启mysql

在命令行中输入bin/mysql进行登录(直接输入mysql命令可能提示找不到命令。因为path路径未设定，后面添加path路径说明。)

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| sys |

+--------------------+

4 rows in set (0.00 sec)

mysql> USE mysql; #选择数据库

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> update user set authentication_string=password('123abc') where user='root';

Query OK, 0 rows affected, 1 warning (0.00 sec)

Rows matched: 1 Changed: 0 Warnings: 1

mysql> flush privileges; #刷新权限

Query OK, 0 rows affected (0.00 sec)

mysql> quit;

Bye

重新登录mysql

[root@CLanguage run]#mysql -uroot -p123abc

修改完成后，注销my.cnf中的“skip-grant-tables”

修改环境变量：

将mysql的bin路径添加到/etc/profile

[root@CLanguage mysql]# vim /etc/profile

添加：

export PATH=/usr/local/src/mysql/bin:$PATH

[root@CLanguage mysql]# source /etc/profile

配置mysql自动启动

[root@CLanguage mysql]#chmod 755 /etc/init.d/mysqld

[root@CLanguage mysql]#chkconfig --add mysqld

[root@CLanguage mysql]#chkconfig --level 345 mysqld on

在使用过程中，发现重启电脑，mysql无法启动。报PID文件找不到，存放PID文件的路径为：/var/run/mysqld下面，每次重启完在/var/run/目录中都找不到mysqld文件夹，都需要重新创建一次mysqld文件夹和修改文件夹的所属用户和组，才能正常使用。

解决方法

因为之所以/var/run/mysqld 目录每次重启后都需要手动去创建，是因为/var/run/目录下建立文件夹是在内存中，故每次重启后内存被清空导致/var/run/mysqld 也被清除，从而导致无法启动mysql。

创建一个mysqld.pid文件存放目录，重新修改文件夹所属用户和组。修改my.cnf文件，找到pid-file=/var/run/mysqld/mysqld.pid将mysqld.pid存放路径修改到其他存放位置。具体操作如下：

重新启动mysql正常运行。