Why Databases: Data, Information and the DBMS

Hello students, welcome to Kwickprep. Imagine your school keeps every student's details in many separate notebooks. A student moves house, and only one notebook gets the new address. Which address is true now? Today we will learn about data and information, the problems with simple files, and how a database management system solves them.

Let us begin with two words that exams love to ask. Data means raw facts, like numbers, names and dates, that have no clear meaning on their own. Information is data that has been processed, so it becomes meaningful and useful. The marks eighty eight, seventy six and ninety one are data, but the class average of eighty five is information.

Here is how data turns into information. First, the teacher collects the raw marks of every student. Next, the computer adds each student's marks and compares the totals. Finally, it prints a merit list, which tells us who came first. That merit list is information, because it helps us take a decision.

Before databases, most offices stored data in simple files. A file here means a document or a spreadsheet saved on a computer. In a school, the class teacher, the library and the transport office each keep their own separate files. These files are not linked, so a change in one file does not reach the others.

Look at how Riya's details are stored. The class teacher's file has her name and city. The library file stores the same name and city again. The transport file stores them a third time. This repeating of the same data in many places is called data redundancy, and it wastes storage and effort.

Now Riya's family moves to Surat. The class teacher updates her file to Surat. But nobody tells the library, so it still says Ahmedabad. The transport office also still says Ahmedabad, and the school bus goes to the wrong city. When copies of the same data do not match, we call it data inconsistency. Redundancy causes inconsistency.

Files have a few more problems. Searching is slow, and combining data from many files is hard. Security is weak, because anyone who opens the file can change it. If two people edit the same file at once, one person's work can be lost. And if a computer crashes, the data is safe only if someone remembered to take a backup.

The answer to these problems is a database. A database is an organised collection of related data, stored in one place. A D B M S, or database management system, is the software that creates a database and manages it. Popular examples are My S Q L, Oracle, Postgre S Q L and LibreOffice Base.

So what does a D B M S actually do? It stores each fact once and shares it with every user who needs it. Because data is not repeated, copies cannot disagree, so inconsistency is avoided. It uses passwords and permissions to control who can see or change the data. It lets many users work at the same time without losing anyone's work. It also takes backups and recovers data after a failure.

Here is a school that uses a database. The Student table stores each student's name, class and city only once, and every office reads it. The Marks table stores exam marks for the class teacher. The Fees table stores fee receipts for the accounts office. The library records the books issued. Now when Riya moves to Surat, the city is changed once, and every office sees Surat.

Indian Railways books tickets through one central reservation database. You enter the train and the date, on the railway website, the app or a station counter. The system checks the database, is a seat available? If yes, it books the seat and gives you a P N R number. If no, it offers you a waiting list ticket. Pause and predict. Two people in different cities click the last seat at the same moment. Who gets it? Only one, because the D B M S lets one booking finish before the next one starts.

Let us revise what we learned today. Data is raw facts, and information is processed, meaningful data. Separate files repeat data, which is redundancy, and the copies stop matching, which is inconsistency. A D B M S is software that creates and manages a database. It shares data, controls who can use it, and keeps it backed up. School records and railway reservations are two everyday examples.