 In this module, we'll talk about how to use SQL on the web. And of course, for this, we will use the MySQL database as the database server. And I'll also tell you why we have made that selection for a number of reasons. What are the benefits also? And then we'll very briefly talk about the operations which we'll be performing on that database. So without further ado, I move on and start with deciding how to store the data. Now, storing the data is dependent upon number of factors. And there are about six factors I'll briefly talk about. The factors are how much data is to be stored, how frequently the data is to be stored, how frequently or how often the data changes, and how many users will be simultaneously accessing the data. What will be the growth rate of the data over a period of time? And since the data is on the web, it is globally accessible. So when the security point of view, there are always the aspects of somebody breaking into your database server. So there will be a loss. So how much loss you are willing to sustain? So these are the six factors which are taken into consideration when we decide about how we store the data. Now, once we have decided that how we'll be storing the data, then there are two aspects over here are the database architectures and then the database models. So when we talk about the database architectures over here, we look at the embedded system. Now the embedded system, the database is stored along with the application. And it is stored on the same server, on the same computer. So obviously it will give very good performance because there is no connectivity communication over the net or over a network. So the application is residing on the same server. The database is residing on the same server and it gives very good performance, obviously. Then is the client server model. Now in the client server model, it is obviously the multi user model. It is obviously the communication takes place over the network. It could be internet also. It could be intranet also and because by virtue of separating the client from the server, it adds flexibility to this model. This model is flexible, but of course there will be a communication cost and degradation performance. Then is the database models. So we have the simple database models. We have like simple associative arrays. The data is stored there. It is very simple. It is very simple to process. It is very simple to work with, but it does not have the functionality and it does not have the power which is there in the relational model. In the relational model, we have the tables and the tables are connected together based upon the relationships, based upon the foreign key relationship. And of course then is the primary key also. So we have these two models. We have these two architectures. We'll talk about more detail. Now why different companies select MySQL? So you can see on the screen the reasons why MySQL is selected. MySQL is the database server which we'll be covering in this course. And PHP is the application programming environment or it is the engine, PHP engine that will be used. So it is one of the most popular databases on the web. And of course it's very popular. It is easy to use and it is very functionality. And it is freely available. You can download it, you can install it. There is no license fee. It is easy to install. It is supported by different operating systems, by Unix, by Windows, by MySQL and the list goes on. And the web hosting is very cheap which I discussed in the prior modules. You have to make your application and put it with your ISP or put it with your database server. And it is simple to use and administrator. And this point is very important that it is scalable. It can be used for large projects. It can be used for large applications. And what we'll do in the subsequent modules, we will create a database using MySQL, create table, add data to it, update data to it, delete the data from it, delete the table and also delete the database. I'll show you the commands and you will understand all those things. And finally, making the connection. How do you make the connection with the database? How do you connect them? There are a number of ways of making the connection, handling errors and reading the data and processing whatever comes your way. So the connections can be made. You can access in different ways and we will discuss all the details. And one thing which you will be liking to know is that there are two modes. One is the MySQL and the other is the object database mode. Now I will go into more details but right now what I would like to share with you is that in the MySQL I mode, it is simple to learn. It is powerful to some people but it has so much functionality that people kind of get overwhelmed by it. And on the other hand is the PHP data objects, PDO. With PDO, it has fine functionality. It is simple, it is straightforward and once you become accustomed to using it, then of course you can move on and employ the other modules also and things will become easy for you. So that's for this module.