Ubuntu-18 安装mysql-8

dpkg --list|grep mysql   查看是否有历史安装记录。空则表示没有。若有请清理历史记录。

wget -c https://dev.mysql.com/get/mysql-apt-config_0.8.10-1_all.deb

dpkg -i mysql-apt-config_0.8.10-1_all.deb

默认安装的就是8.0版本，选择OK

apt update

报错，签名过期了

Err:7 http://repo.mysql.com/apt/ubuntu bionic InRelease        
  The following signatures were invalid: EXPKEYSIG 8C718D3B5072E1F5 MySQL Release Engineering <mysql-build@oss.oracle.com>
Reading package lists... Done
W: GPG error: http://repo.mysql.com/apt/ubuntu bionic InRelease: The following signatures were invalid: EXPKEYSIG 8C718D3B5072E1F5 MySQL Release Engineering <mysql-build@oss.oracle.com>
E: The repository 'http://repo.mysql.com/apt/ubuntu bionic InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

解决：删除过期的签名，添加新的

apt-key list

 apt-key del rsa4096

重新添加签名：

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 8C718D3B5072E1F5

重新更新：

apt update

安装mysql8：

apt install mysql-server

输入之后会出现选择加密方式的提示界面，我在网上的教程中看到默认的mysql8.0的加密方式与ubuntu18.04 不兼容，所以选择5.x的加密方式；建议选择下边的那个。

安装完，试试：

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> show variables like '%low%';
+----------------------------+-----------------------------------+
| Variable_name              | Value                             |
+----------------------------+-----------------------------------+
| log_slow_admin_statements  | OFF                               |
| log_slow_extra             | OFF                               |
| log_slow_slave_statements  | OFF                               |
| low_priority_updates       | OFF                               |
| lower_case_file_system     | OFF                               |
| lower_case_table_names     | 0                                 |
| max_allowed_packet         | 67108864                          |
| mysqlx_max_allowed_packet  | 67108864                          |
| slave_allow_batching       | OFF                               |
| slave_max_allowed_packet   | 1073741824                        |
| slow_launch_time           | 2                                 |
| slow_query_log             | OFF                               |
| slow_query_log_file        | /var/lib/mysql/dev-TBC63-slow.log |
| transaction_allow_batching | OFF                               |
+----------------------------+-----------------------------------+
14 rows in set (0.01 sec)

mysql>  show variables like "%char%";
+--------------------------+--------------------------------+
| Variable_name            | Value                          |
+--------------------------+--------------------------------+
| character_set_client     | utf8mb4                        |
| character_set_connection | utf8mb4                        |
| character_set_database   | utf8mb4                        |
| character_set_filesystem | binary                         |
| character_set_results    | utf8mb4                        |
| character_set_server     | utf8mb4                        |
| character_set_system     | utf8                           |
| character_sets_dir       | /usr/share/mysql-8.0/charsets/ |
+--------------------------+--------------------------------+
8 rows in set (0.00 sec)

mysql> 

大小写敏感的需要修改配置文件。

配置文件：

停止服务：

systemctl stop mysql.service

修改配置：

vi /etc/mysql/mysql.conf.d/mysqld.cnf

增加一行
lower_case_table_names = 1

启动：

systemctl start mysql.service