How to implement the database level of a web application`

If you are wondering on how to design database level of a web application, then first thing you want to do is to identify the different classes of the application[i will be explaining to which i am referring to as classes if you are not quite sure about this term]. Identifying different classes in your system is done as follows. Here is a real world synario to identify different classes. Lets consider that we want to implement free online educational system which provide university level ordered education to any one who seek knowledge. So, this big picture is the primary key in designing the database. So , you should be having clear idea on what you are going to do. So first question your self by asking very basic questions ,

Who are the users of this system.

What exactly i am going to offer to the target users of this system.

What are the existing applications similar what we are doing.

How does this product differ from those existing sites.

And do research on web application that might provide different service to the user than what you are doing to understand how if they have become successful and why if they have become unsuccessful. Then, compare your goal with how others have achieved there goal in a web application.

Target users of a free online educational system is university students of IT field at very first stage. i would like to compare this with stackoverflow.com, since it is been the most successful forum for developers to find exact answers for the technical problems they are facing in the industry. so stack-overflow has been successful by gathering talented software engineers around the world. And key point that handle the success of stack-overflow is that it is active, if you type question at stackoverflow.com, you get answers with in seconds. That is one reason developers are emotionally attached to it.