Mysql

Connect to a db host:

mysql -u user -h db.host.com -p

List databases:

show databases;

Move into a db and list tables:

use foo;
show tables;

Examine data:

DESCRIBE wiki_user;
select user_name from wiki_user;
select user_id, user_name, user_real_name, user_email from wiki_user;
select * from wiki_user where user_name = "Dre";

List all user-contributed wiki stories (in this wiki, cur_id of user contrib'd pages starts at 928)

select cur_title, cur_id from wiki_cur where cur_id > 927;

Show text of an entry

select cur_title, cur_text from wiki_cur where cur_id = 930;

Backup / Restore

mysqldump -u user -h db.host.com -p database > dump.sql
mysql -u user -h db.host.com -p database < backup-file.sql