Introduction to DBMS

A database is a collection of related data organized in a structured and meaningful way. Proper organization allows faster:

• Storage (entry)
• Access
• Update
• Manipulation

For example: imagine a phonebook with 1,000,000+ contacts stored in random order. Without organization (e.g., alphabetical indexing), finding or updating entries would be slow. A properly structured database arranges related fields (name, phone, address) together so operations like search, insert, and update are efficient.

Early databases were often stored on sequential media like magnetic tapes. These were effectively read-only for practical purposes — updates, deletions, or inserts were difficult and slow.

As the need for flexible data storage and management grew, database systems evolved into fully managed software solutions. Commercial relational database systems (such as early Oracle products) emerged to address these limitations.

A Database Management System (DBMS) is software that controls the storage, retrieval, modification and administration of data in a database. It provides tools to create, update, define and secure databases.

Common examples of DBMS products:

• SQL (as a language)
• MySQL
• NoSQL systems (e.g., MongoDB)
• Oracle
• IBM Db2
• PostgreSQL

A DBMS typically supports:

• Database definition
• Data update
• Data retrieval
• Administration
• Security

This defines how data is organized. Example: creating a student database for PrepInsta might include fields like:

• Unique user ID
• Email address
• First name
• Last name
• Password (stored securely)

Data manipulation includes operations such as inserting, updating and deleting records in database tables.

• Insertion – e.g., adding a new user who signs up on a site.
• Updation – e.g., changing a user's password when requested.
• Deletion – e.g., removing account data when a user deletes their account.

Data retrieval refers to fetching stored data for various operations — for example, checking credentials during login requires querying database tables.

Typical roles and permissions in a DBMS:

• Database Administrator (DBA) – full privileges: create, modify, delete, backup and restore.
• Database Manager – define and update structures, but with limited destructive privileges.
• Database Editor – insert and retrieve data, limited schema privileges.

Security is critical. Authentication, authorization, encryption and auditing prevent unauthorized access or tampering of sensitive data.