Linux上安装mysql8.0，安装过程及遇到的错误总结

安装过程，不再赘述，参考https://blog.csdn.net/qq_31382921/article/details/53696031
以及https://blog.csdn.net/u012946310/article/details/81880050问题都能解决；
特别注意：mysql启动服务是service mysqld start 是mysqld不是mysql。

一、mysql安装过程

补充安装过程：（之前安装好了之后，发现第二次安装又遇到不成功的问题，随将过程大概记录一下）

1. 检查系统里面之前有没有安装过mysql数据库，为了防止卸载不干净，导致安装失败，先进行检查

基本rpm使用语句：

1. 查看有没有旧版本 的mysql rpm -qa | grep -i mysql
2. 卸载旧版本的mysql rpm -ev mysql-libs-5.1.71-1.el6.x86_64
3. 2019/06/17刚发现的批量卸载命令：rpm -qa | grep -i mysql | xargs rpm -ev --nodeps
   如果无法卸载，请加上 --nodeps,忽略依赖，进行强制卸载
4. 查找mysql 文件的出现过的安装位置 find / -name mysql，其中配置文件/etc/my.cnf需要手动删除

[root@localhost mysql]# rpm -qa | grep -i mysql                           
mysql-community-libs-compat-8.0.15-1.el6.x86_64
mysql-community-common-8.0.15-1.el6.x86_64
mysql-community-libs-8.0.15-1.el6.x86_64
mysql-community-client-8.0.15-1.el6.x86_64

[root@localhost mysql]# rpm -ev mysql-community-libs-compat-8.0.15-1.el6.x86_64 --nodeps
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient_r.so.16.0.0 failed: No such file or directory
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient_r.so.16 failed: No such file or directory
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient.so.16.0.0 failed: No such file or directory
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient.so.16 failed: No such file or directory

[root@localhost mysql]# rpm -qa | grep -i mysql
mysql-community-common-8.0.15-1.el6.x86_64
mysql-community-libs-8.0.15-1.el6.x86_64
mysql-community-client-8.0.15-1.el6.x86_64

[root@localhost mysql]# rpm -ev mysql-community-common-8.0.15-1.el6.x86_64 --nodeps

[root@localhost mysql]# rpm -ev mysql-community-libs-8.0.15-1.el6.x86_64 --nodeps
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient.so.21.0.15 failed: No such file or directory
warning:    erase unlink of /usr/lib64/mysql/libmysqlclient.so.21 failed: No such file or directory
warning:    erase unlink of /usr/lib64/mysql failed: No such file or directory

[root@localhost mysql]# rpm -ev mysql-community-client-8.0.15-1.el6.x86_64 --nodeps
warning:    erase unlink of /usr/bin/mysql failed: No such file or directory

[root@localhost mysql]# rpm -qa | grep -i mysql                                      
[root@localhost mysql]# ll

2.将官网下载的源码安装包，解压，有7个安装解压后的.rpm文件，只需要按顺序安装4个就好了

[root@localhost mysql]# ll
total 1054072
-rw-r--r--. 1 root root  539678720 Apr 14 07:21 mysql-8.0.15-1.el6.x86_64.rpm-bundle.tar
-rw-r--r--. 1 7155 31415  28906084 Jan 27 04:58 mysql-community-client-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415    705768 Jan 27 04:58 mysql-community-common-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415   4258376 Jan 27 04:58 mysql-community-devel-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415   2543044 Jan 27 04:58 mysql-community-libs-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415   1769320 Jan 27 04:58 mysql-community-libs-compat-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415 414585640 Jan 27 04:58 mysql-community-server-8.0.15-1.el6.x86_64.rpm
-rw-r--r--. 1 7155 31415  86903628 Jan 27 04:59 mysql-community-test-8.0.15-1.el6.x86_64.rpm
[root@localhost mysql]# rpm -ivh mysql-community-common-8.0.15-1.el6.x86_64.rpm
warning: mysql-community-common-8.0.15-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                ########################################### [100%]
   1:mysql-community-common ########################################### [100%]
[root@localhost mysql]# rpm -ivh mysql-community-libs-8.0.15-1.el6.x86_64.rpm
warning: mysql-community-libs-8.0.15-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                ########################################### [100%]
   1:mysql-community-libs   ########################################### [100%]
[root@localhost mysql]# rpm -ivh mysql-community-client-8.0.15-1.el6.x86_64.rpm
warning: mysql-community-client-8.0.15-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                ########################################### [100%]
   1:mysql-community-client ########################################### [100%]
[root@localhost mysql]# rpm -ivh  mysql-community-server-8.0.15-1.el6.x86_64.rpm
warning: mysql-community-server-8.0.15-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                ########################################### [100%]
   1:mysql-community-server ########################################### [100%]

3.启动mysql服务，service mysqld strat

[root@localhost mysql]# service mysqld start
Initializing MySQL database:                               [  OK  ]
Starting mysqld:                                           [  OK  ]

4. 查看mysql的初始密码

less /var/log/mysqld.log 找出文件的内容A temporary password is generated for root@localhost: yRXtgZdm&3;t 冒号后面就是初始密码

5. 进入mysqlmysql -uroot -p

输入初始密码，成功进入mysql

6.重置密码

特别注意在mysql8.05以后的版本中，貌似只能用
命令： ALTER USER ‘root’@‘localhost’ IDENTIFIED WITH mysql_native_password BY ‘password’;
或者用 ALTER USER ‘root’@‘localhost’ IDENTIFIED WITH BY ‘password’;
实在不行： （有毒，明明之前就可以，重新安装使用这些命令就又不对了，听天由命吧，挨着试一下）

mysql> alter user 'root' identified by '123456';
Query OK, 0 rows affected (0.04 sec)

1> 利用初始密码进入mysql，后需要立马修改root的密码，否则无法使用，不然会报如下错误。

ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

如果只是修改为一个简单的密码，会报以下错误：

ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

原因是因为密码设置的过于简单会报错,MySQL有密码设置的规范，具体是与validate_password_policy的值有关,下图表明该值规则

validate_password_policy有以下取值：

默认是1，即MEDIUM，所以刚开始设置的密码必须符合长度，且必须含有数字，小写或大写字母，特殊字符。

有时候，只是为了自己测试，不想密码设置得那么复杂，譬如说，我只想设置root的密码为123456。

如果想要查看MySQL完整的初始密码规则,登陆后执行以下命令

mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+-------+
| Variable_name                        | Value |
+--------------------------------------+-------+
| validate_password.check_user_name    | ON    |
| validate_password.dictionary_file    |       |
| validate_password.length             | 4     |
| validate_password.mixed_case_count   | 1     |
| validate_password.number_count       | 1     |
| validate_password.policy             | LOW   |
| validate_password.special_char_count | 1     |
+--------------------------------------+-------+
7 rows in set (0.01 sec)

查看全局参数，发现mysql8.0之后修改为了validate_password.length 而不是之前的validate_password_policy，怪不得用网上的命令修改，老是报错，因为变量名称变化了_变成了 .
2> 密码的长度是由validate_password.length决定的,但是可以通过以下命令修改

**set global validate_password.length=4;**

3> 密码的验证策略由validate_password.policy决定,默认等级为MEDIUM(中等),可通过以下命令修改为LOW(低)

**set global validate_password.policy=0;**

修改完成后密码就可以设置的很简单，比如123456之类的。
4> mysql8.0之后修改root密码，我测试只有用
ALTER USER ‘root’@‘localhost’ IDENTIFIED WITH mysql_native_password BY ‘password’;
或者用 ALTER USER ‘root’@‘localhost’ IDENTIFIED WITH BY ‘password’;好使！！！
而且远程登录的ip地址，在这里不能写任意%，否则会修改失败。如果需要改为任意远程地址都可以的%，则可以进入mysql库，利用update 更新user表来实现，最后刷新一下权限!!!

**mysql> use mysql 
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 host = '%' where user ='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)**

5> 总结：
至此8.0以后的mysql数据库，虽然命令有所变化，但按照上述的步骤都可以修改root用户为简单密码，且只要服务器能ping通，端口能telnet通，装有mysql客户端，则任意ip地址都能远程连接到该mysql的数据库服务器。

二、遇到的错误

远程登陆失败的问题

安装完成后在windos系统上利用Navcat客户端连接mysql数据库，在数据库ip地址和端口号都正确的情况下，且确定linux的防火墙关闭，报错: 2003——can’t connect to mysql server on IP(10060)
大概意思就是，这个IP没有远程连接mysql权限。
查询资料多数让使用mysql语句
GRANT ALL PRIVILEGES ON . TO ‘root’@’%’ IDENTIFIED BY ‘123456’ WITH GRANT OPTION;
但是，亲测无效，说是语法错误。可参考：https://www.cnblogs.com/zhangzhu/archive/2013/08/22/3274831.html
https://www.cnblogs.com/stxs/p/8675390.html

于是在cmd上telnet ip 端口，发现报错为：

我的linux系统ip是192.168.197.134，网关是192.168.197.1
报错信息时：链接mysql时:Host ‘gateway’ is not allowed to connect to this MySQL server;

最终，使用以下办法成功解决：

mysql> use mysql;
Database changed
mysql> select 'host' from user where user='root'
    -> ;
+------+
| host |
+------+
| host |
+------+
1 row in set (0.00 sec)
 
mysql> update user set host = '%' where user ='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
 
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
 
mysql> select 'host'   from user where user='root';
+------+
| host |
+------+
| host |
+------+
1 row in set (0.00 sec)

参考文章：https://blog.csdn.net/me_Lany/article/details/82770948

测试后，发现Navcat也可以成功连接！
**

干货总结： 就4条命令解决，远程授权，登录不上的问题。

在Linux上，登录mysql - 选择数据库 - 更新user表 - 立即生效！

**

[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 21
Server version: 8.0.15 MySQL Community Server - GPL

Copyright (c) 2000, 2019, 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> use mysql
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 host = '%' where user ='root';
Query OK, 1 row affected (0.07 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)