SQL Introduction

SQL Introduction

What Data?

Data refers to raw facts, figures, or symbols that can be processed to generate useful information. Data can come in many forms, such as numbers, text, images, audio, or video. 'Data' originated from 'datum', which means 'single piece of information.' It is the plural of the word datum.

Example: employee IDs and salaries are all examples of data.

What Database?

A database is a structured collection of data organized for efficient storage, retrieval, and management. It allows data to be stored systematically so that users can quickly access and manipulate the data when needed.

Example: A company database might store information about employees, departments, products, and customers.

What is SQL?

SQL (Structured Query Language) is a programming language that allows users to store, read, and update data in a relational database. SQL is a standardized language that interacts with RDBMS (Relational Database Management System). SQL is used to perform all types of data operations in RDBMS.

History -

  • 1970 - E. F. Codd publishes the relational model paper, forming the foundation for SQL.
  • 1974 - IBM begins work on SEQUEL as part of the System R project.
  • 1979 - Relational Software, Inc. (now Oracle) releases the first commercial SQL database.
  • 1981 - IBM introduces SQL/DS, one of the first commercial implementations of SQL.
  • 1986 - SQL becomes a standardized language by ANSI (American National Standards Institute).
  • 1987 - SQL is recognized as an ISO (International Organization for Standardization) standard.
  • 1990s to present - SQL standards evolve, adding features like triggers, stored procedures, and XML support. SQL is now the standard language for managing relational databases.

Advantages -

  • Standardized Language: SQL is an ANSI and ISO standard, making it widely accepted and used across databases.
  • High Speed: SQL allows for quick retrieval of large data sets.
  • Declarative Language: Focuses on what to retrieve instead of how to retrieve it.
  • Interactive and Easy to Use: SQL is relatively easy to learn and allows for interactive data querying.
  • Supports Multiple Views: Different users can access different views of the same data.

Disadvantages -

  • Complexity for Non-Technical Users: SQL can be challenging for users without a technical background.
  • Limited Control: SQL operates at a high level, which can make fine-tuned control difficult for large applications.
  • Vendor Variability: SQL implementations can vary between vendors, causing portability issues.

Why is SQL used?

SQL is essential for managing and interacting with relational databases due to its features and simplicity. Here are a few reasons why SQL is widely used:

  • Efficient Data Management: SQL can handle large amounts of data efficiently, making it ideal for organizations managing complex data.
  • Versatile and Universal: SQL can work with many different databases, enabling data portability and flexibility.
  • Structured and Easy to Learn: SQL is straightforward and easy to learn, making it accessible for both technical and non-technical users.
  • Data Integrity and Security: SQL has features that ensure data integrity and support security measures like user permissions.

Applications that use SQL

Many applications across different industries and domains rely on SQL to manage data in relational databases. Examples of Applications Using SQL:

  • Banking and Finance
  • E-Commerce
  • Healthcare
  • Education
  • Customer Relationship Management (CRM)
  • Social Media Platforms