Ubuntu/mysql

mysql is one of the most popular database applications on the market today

mysql login

mysql -u <user> -p

will then prompt you for a password
mysqladmin login

mysqladmin -u <user> -p

you can also run other commands after -p, such as:
see if the database is running

status

change MySQL root pass

sudo dpkg-reconfigure mysql-server-5.1

verify MySQL is running

sudo netstat -tap | grep mysql

backup wiki mysql database

sudo -s
mysqldump -u user -p db.name > wikidatabasebackup.sql
i.e. mysql -u wikiuser -p wikidb > /var/www/mediawiki/backup/wikidatabasebackup10_4_12.sql

view all databases

~$ mysql -u root -p
~mysql>SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema | 
+--------------------+
3 rows in set (0.00 sec)

delete (drop) a database

~mysql> DROP DATABASE IF EXISTS <db name>;
Query OK, 11 rows affected (0.04 sec)

list all users

~mysql> SELECT User,Host FROM mysql.user;
+------------------+-----------------+
| User             | Host            |
+------------------+-----------------+
| root             | 127.0.0.1       |
| root             | ::1             |
| root             | mysite |
| debian-sys-maint | localhost       |
| root             | localhost       |
+------------------+-----------------+
5 rows in set (0.00 sec)

delete a user

~mysql> DROP USER 'wordpress'@'localhost';
Query OK, 0 rows affected (0.00 sec)