SQL serves as a general programming language that operates databases. Before delving into SQL, it is essential to grasp the fundamentals of databases.

Importance of Data

Data is often likened to the new oil. Business evolution traverses three key stages:

  1. Computer: Functioning on data.
  2. Internet: Generating data.
  3. AI: Constructed with data.

In every steps data is used. Data are stored in Database.

What are Databases?

Databases are software designed to organize, manage, and store data. The standout feature is the ability to retrieve data in any desired format.

Database Usage

  1. Data Storage: Utilized for storing large amounts of unstructured data, ensuring easy accessibility, searchability, and retrieval.
  2. Data Analysis: Enables complex data analysis, report generation, and provides insights into the data.
  3. Record Keeping: Often employed for tracking crucial records, such as financial transactions and customer information.
  4. Web Application: Constitutes a critical component for web applications, facilitating dynamic content and user management.

Regardless of the complexity of the database structure, CRUD operations (Create, Update, Retrieve, and Delete) are employed—a notable aspect of database functionality.

Properties of Databases

  1. Integrity: Ensuring accuracy and consistency.
  2. Availability: Operational 24/7.
  3. Security: Paramount importance.
  4. Independence of Application: Facebook stores user information, including the same user ID, across different devices in a common database. This enables users to make changes from one device and see those changes reflected on another device.
  5. Concurrency (Parallel): Facilitates simultaneous data retrieval for users seeking information concurrently.

Types of Databases

  • Relational Databases:

Also known as SQL databases, these types organize data into tables with rows and columns, following a relational model.

  • NOSQL Databases:

Specifically designed for managing a large volume of unstructured data, including images, videos, and documents. An example is MongoDB.

  • Column Databases:

These databases store data in columns rather than rows, making them particularly suitable for data warehousing and analytical applications.

  • Graph Databases:

These databases store data in a graphical structure, which is beneficial for representing social network connections or recommendations.

  • Key-Value Databases:

These databases store data in key-value pairs, making them well-suited for tasks like caching and simple data storage needs.

How Data is Stored in Databases?

  • In a database, data is organized into a series of records. Each database record consists of smaller units of data called segments. A segment, in this context, is the smallest piece of data that the database management system (IMS) can store.

Functions of Database Management System

  • Data Management:

Responsible for storing, retrieving, and modifying data within the database, ensuring efficient handling of information.

  • Integrity:

Ensures the accuracy and consistency of data, maintaining the reliability of information stored in the database.

  • Concurrency:

Facilitates simultaneous access to data for multiple users, allowing multiple individuals to interact with the database concurrently.

  • Transaction:

Ensures that modifications to the database are either successful or do not occur at all. For example, in a monetary transaction, if your friend sends money to you and you don’t receive it, the transaction will revert to your friend’s account.

  • Security:

Controls access to the database, permitting entry only to authorized users. This safeguards sensitive information from unauthorized access.

  • Utilities:

Manages various utility functions such as data import/export, user management, backup processes, and logging activities, enhancing the overall administration and maintenance of the database.

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