Show MySQL uptime:
mysqladmin version

Login to MySQL
mysql -h [hostname] -u [username] -p

Show databases
show databases;

Create database
create database [name];

Delete database
drop database [name];

Use database
use [database];

Show tables
show tables;

Show columns
show columns from [table];

Find and replace string
update [table_name] set [column_name] = replace([column_name],'[string_to_find]','[string_to_replace]');

To backup and restore a mysql database see one of my earlier posts here:
http://www.homecomputerlab.com/backing-up-mysql-databases