Docker failed to start the container after installing mysql. Check the MySQL container log and find:

[ERROR] [FATAL] InnoDB: Table flags are 0 in the data dictionary but the flags in file ./ibdata1 are 0x4800!

Query all containers

docker ps -a

Delete container

docker rm CONTAINER ID;  #CONTAINER ID is the actual container number

If so, be sure to delete the external mount directory.

Restart mysql. I installed version 5.7 of MySQL

docker run -p 3306:3306 --name mysql \
-v /mydata/mysql/log:/var/log/mysql \
-v /mydata/mysql/data:/var/lib/mysql \
-v /mydata/mysql/conf:/etc/mysql \
-e MYSQL_ROOT_PASSWORD=root \
-d mysql:5.7

Enter the container external mount profile

vim /mydata/mysql/conf/my.conf

Insert the following. Copy the following contents. After entering the file through the previous operation, press keyboard I to enter the insertion state, shift + insert to paste the contents, ESC to exit the insertion mode,: WQ save and exit

[client]
default-character-set=utf8
[mysql]
default-character-set=utf8
[mysqld]
init_connect='SET collation_connection = utf8_unicode_ci'
init_connect='SET NAMES utf8'
character-set-server=utf8
collation-server=utf8_unicode_ci
skip-character-set-client-handshake
skip-name-resolve

Restart MySQL

docker restart mysql