44 total
By the end of this subtopic, you should be able to:
A Database Management System (DBMS) is a type of system software used to define, create, and manage a database. In simple words, it is the software that helps people store data in an organised way and then find, change, or delete that data when needed.
A database is useful because a lot of information can be kept together in one place. For example, a school might store data about pupils, teachers, classes, and rooms. A shop might store data about products, customers, and orders. The DBMS helps users work with all of this data properly.
A DBMS does much more than just save information. It also helps organise data, protect it, control who can use it, and make sure it stays accurate.
Before databases were widely used, many organisations stored data using a file-based approach. This means each application or program kept its own separate files.
For example, imagine a school has:
At first this may seem fine, but it creates several problems.
Data redundancy means the same piece of data is stored more than once.
For example, a pupil’s name and class might appear in the attendance file, the exam file, and the timetable file. This wastes storage space. It also makes the system harder to manage because the same data appears again and again.
A DBMS reduces redundancy by storing data in linked tables. Most pieces of data are stored only once, and tables are connected using keys such as foreign keys. This means less unnecessary copying of data.
Data inconsistency happens when the same data has different values in different places.
For example, if a pupil changes address, one file may be updated but another file may still show the old address. Now the system contains conflicting information.
A DBMS helps solve this because most data is stored once. When that one value is updated, all users and applications can see the new version. This improves accuracy and avoids confusion.
Data dependency means programs depend too much on the exact structure of the files.
For example, if a field is added, removed, or moved inside a file, the application programs that use that file may stop working or may need to be rewritten.
A DBMS reduces this problem because the data is managed separately from the applications. If the structure changes, the DBMS handles that change. Applications that do not use the changed table or field are not affected.
In a file-based system, getting data in a useful form can be difficult. A program may have been written for one specific purpose only. If a user wants the data in a new format, another program may need to be created.
A DBMS makes this easier by allowing users or developers to ask questions, called queries, to retrieve exactly the data they need. This makes data much more flexible and useful.
Sign in to view full notes