Added mysql notes to the knowledge base

knowledge base/mysql.md

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+# MySQL
+
+## TL;DR
+
+```shell
+# connect with user "root" on the local default socket
+# don't ask password and do not select db
+mysql
+
+# connect with user "user" on the local default socket
+# ask for a password and execute a command
+mysql -u user -p -e 'show databases;'
+
+# provide a password on the cli
+# put no spaces between -p and the password
+mysql -u ${USERNAME} -h ${HOST} -p${PASSWORD} ${DATABASE}
+```
+
+```sql
+-- list the available databases
+SHOW DATABASES;
+SHOW DATABASES LIKE 'open%';
+
+-- list tables in the pizza_store database
+use pizza_store;
+show tables;
+
+-- give permissions
+grant ALL on db.* to 'username'@'localhost' identified by 'password';
+grant ALL on db.* to 'username'@'127.0.0.1';
+```
+
+## Further readings
+
+- How to [list tables] in MySQL
+- How to [show databases] in MySQL
+- [phpimap issue 1549]
+
+[list tables]: https://alvinalexander.com/blog/post/mysql/list-tables-in-mysql-database/
+[show databases]: https://linuxize.com/post/how-to-show-databases-in-mysql/
+[phpimap issue 1549]: https://github.com/phpipam/phpipam/issues/1549