#### Show all databases: ####
show databases;

#### List databases size: ####
SELECT table_schema AS "Database name", SUM(data_length + index_length) / 1024 / 1024 AS "Size (MB)" FROM information_schema.TABLES GROUP BY table_schema;

#### Reset root password: ####
service mysql stop
mysqld_safe --skip-grant-tables &
mysql -u root
mysql> USE mysql;
mysql> UPDATE USER SET password=PASSWORD("NEW-ROOT-PASSWORD") WHERE User='root';
mysql> FLUSH PRIVILEGES;
mysql> quit
mysqladmin shutdown
service mysql start
mysql -u root -p