Introduction to SQL
SQL (Structured Query Language) is the standard language used to communicate with relational databases. It allows users to create, read, update, and delete data—often abbreviated as CRUD operations.

Why Learn SQL?
SQL is essential for:

  • Data analysts who need to query large datasets
  • Backend developers managing application data
  • Anyone working with databases like MySQL, PostgreSQL, SQL Server, or SQLite

Basic Concepts

  1. Databases and Tables A database is a collection of related data, and a table is a structured format to store that data—rows (records) and columns (fields).

Example of a students table:

id name age
1 Alice 20
2 Bob 22
Common SQL Commands
SELECT
Retrieves data from one or more tables.

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SELECT name, age FROM students;
WHERE
Filters rows based on a condition.

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SELECT * FROM students WHERE age > 21;
INSERT
Adds new data into a table.

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INSERT INTO students (name, age) VALUES ('Charlie', 23);
UPDATE
Modifies existing data.

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UPDATE students SET age = 21 WHERE name = 'Alice';
DELETE
Removes data from a table.

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DELETE FROM students WHERE name = 'Bob';
Advanced Topics (For Later Learning)
JOINs – Combine rows from multiple tables

GROUP BY – Aggregate data by group

Indexes – Improve query performance

Normalization – Efficient database design

Final Thoughts**
SQL is a foundational skill for working with data. It’s easy to start with and widely applicable across industries. Mastering even the basics can help unlock the full potential of your data.