Mysql key - Super Key, Candidate Key, Foreign key, Primary key

Candidate key:

A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table.

In other words Candidate keys are all columns in a table that are not dependent on other columns in the table. All candidate keys are not primary keys. We choose one of the candidate keys as primary key. A table may contain more than one candidate key but only one primary key column per table is allowed.

Mysql - Learn mysql easily with command

In database system mysql is popular one. It is easy to learn. One thing remind for database, maintainence and security is more difficult. Here is a simple tutorial with mysql commands. How to start first. This tutorial begins post installation of mysql. I use mysql in command prompt. I also use mysql from easyphp software. But you can do it your mysql software.
First install your mysql software. Now tell me what is your Harddisk location of your mysql installation.My mysql mysql installation folder is D:\EasyPHP5.2.10\mysql\

Click Start - All Programs - Acessories - Command Prompt.
After starting your command prompt you see like this
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
F:\Documents and Settings\Administrator>

(click on the command you will see the output)