So who creates databases? A teacher may store the grades of her students in Microsoft Excel. Even that is a database. But this is a database created and used by a single user. Organizations have databases about their employees, customers, suppliers, locations and the like and that is an enterprise database.

Data is stored centrally and accessed simultaneously by multiple users. Complex enterprise databases have teams of programmers, administrators, archi-tects and other experts to create and maintain the database.

In most of the modern systems, you do not directly access the database. There is generally an application that you access, and the application interfaces with the database for you. For example, the railways maintain databases on trains, timings and reservation status. When you use the IRCTC Web application at https://www.irctc. co.in/, you access the database(s) through the application.

Evolution

Initially we used to have the multi-user database stored at one location, though it could be accessed from multiple locations. Now we have the concept of distributed databases, where one single database is stored in multiple computers. The multiple computers hosting that database may or may not be at the same location.

Distributed databases have their own advantages; you can read the Wikipedia article on this topic for details at change to: http://ld2.in/3z6 You can also integrate multiple independent databases into one federated database http://ld2.in/3z7

Impact

Earlier I used to maintain my contact details on a paper-and-pen based address book. Then I shifted to what at that time was popular as “digital diary”. With the advent of mobile phones the digital diary made an unceremonious exit – I not only could store my contacts database, I could pull out a contact with ease and dial the same from the system directly.

Now that I use an Android phone, my contacts database automatically syncs up with my Gmail account – I need to make a change to either my Gmail account or my mobile, and in some time the change is reflected at the database at the other end. What is more, I use Skype as my instant messenger, linked in for my social/business networking, and tweet at the same time. My phone treats all contacts as contacts – whether from Gmail, Skype, linked in or Twitter and shows it as one single database. Does not matter how I contacted my contact!