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2️⃣ 🔎 MySQL SQL Fundamentals – Learn Core SQL for MySQL (2025 Guide)

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🧲 Introduction – Why SQL Matters in MySQL?

Structured Query Language (SQL) is the standard language for interacting with relational databases like MySQL. Whether you’re querying user data, filtering records, or performing aggregations, mastering SQL is essential for database management, reporting, and back-end development.

🎯 In this guide, you’ll learn:

• The foundational SQL commands used in MySQL
• How to retrieve, filter, and sort data effectively
• Logical and comparison operators for complex queries
• Aggregate functions, aliases, and conditional logic

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📘 Topics Covered

🔹 Topic	📄 Description
📜 MySQL Overview	Core concepts of SQL in the MySQL environment
🔍 MySQL SELECT Statement	Retrieve data from tables
📌 MySQL WHERE Clause	Filter records using conditions
🔁 MySQL Logical Operators	Combine conditions with AND, OR, NOT
🔎 MySQL Comparison Operators	Use IN, BETWEEN, LIKE, IS NULL, etc.
🧱 MySQL Sorting & Limiting	Sort results and restrict output size
🧾 MySQL Aliases & Comments	Rename columns/tables and add query comments
🧮 MySQL CASE, ANY, ALL, EXISTS	Implement advanced condition handling
📊 MySQL Aggregate Functions	Perform data calculations (SUM, COUNT, etc.)

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📜 MySQL SQL Overview

SQL (Structured Query Language) is used to create, read, update, and delete (CRUD) data in MySQL databases. The SQL syntax in MySQL supports both ANSI standard SQL and MySQL-specific extensions.

🧩 Types of SQL Statements:

• Data Query Language (DQL): SELECT
• Data Definition Language (DDL): CREATE, ALTER, DROP
• Data Manipulation Language (DML): INSERT, UPDATE, DELETE
• Data Control Language (DCL): GRANT, REVOKE

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🔍 MySQL SELECT Statement

The SELECT statement fetches data from one or more tables.

SELECT name, age FROM users;

🧠 Key Features:

• Select all columns with *
• Combine with WHERE, ORDER BY, GROUP BY, etc.
• Supports joins and subqueries

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📌 MySQL WHERE Clause

Used to filter rows based on a condition.

SELECT * FROM employees WHERE department = 'Sales';

📌 Use Case: Display records that meet certain criteria before applying sorting or aggregation.

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🔁 MySQL Logical Operators (AND, OR, NOT)

Used within WHERE to build complex filtering logic.

SELECT * FROM orders WHERE amount > 500 AND status = 'confirmed';

✅ Operators:

• AND: All conditions must be true
• OR: Any condition must be true
• NOT: Negate a condition

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🔎 MySQL Comparison Operators

Allow you to test values with greater flexibility:

Operator	Purpose	Example
IN	Matches any value in a list	WHERE country IN ('US', 'UK')
BETWEEN	Checks a range	WHERE age BETWEEN 18 AND 30
LIKE	Pattern matching	WHERE name LIKE 'A%'
IS NULL	Checks for null values	WHERE email IS NULL
NOT NULL	Checks for non-null	WHERE phone IS NOT NULL

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🧱 MySQL Sorting & Limiting

🔽 ORDER BY

Sort results in ascending or descending order.

SELECT * FROM products ORDER BY price DESC;

🧮 LIMIT

Limit number of records returned.

SELECT * FROM products LIMIT 5;

🧹 DISTINCT

Remove duplicate values in result set.

SELECT DISTINCT city FROM customers;

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🧾 MySQL Aliases & Comments

✏️ Aliases

Use AS to rename columns or tables for clarity.

SELECT first_name AS Name FROM users;

💬 Comments

Add inline documentation to queries:

-- This fetches all customers from New York
SELECT * FROM customers WHERE city = 'New York';

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🧮 MySQL CASE, ANY, ALL, EXISTS

✅ CASE

Conditional logic inside queries.

SELECT name,
       CASE 
         WHEN salary > 5000 THEN 'High'
         ELSE 'Low'
       END AS SalaryCategory
FROM employees;

🔎 EXISTS

Check if subquery returns rows.

SELECT * FROM employees
WHERE EXISTS (SELECT * FROM departments WHERE dept_id = employees.dept_id);

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📊 MySQL Aggregate Functions

Function	Description	Example
COUNT()	Counts number of rows	SELECT COUNT(*) FROM orders;
SUM()	Adds values in a column	SELECT SUM(amount) FROM orders;
AVG()	Average of column values	SELECT AVG(score) FROM students;
MIN()	Minimum value	SELECT MIN(age) FROM users;
MAX()	Maximum value	SELECT MAX(price) FROM products;

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📌 Summary – Recap & Next Steps

SQL is the foundation of working with MySQL databases. It enables powerful data retrieval, conditional filtering, sorting, and summarizing of data for applications and reports. Learning these core SQL commands is the first step in becoming proficient in database operations.

🔍 Key Takeaways:

• SELECT, WHERE, and logical operators are essential for queries
• Aggregation and sorting add analysis power
• SQL is the language behind MySQL’s power

⚙️ Real-World Relevance:
From fetching customer data to creating dashboards or generating invoices, SQL fundamentals are essential in every backend, analytics, and data role.

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❓ FAQs – MySQL SQL Fundamentals

❓ What is SQL in MySQL?
✅ SQL is the standard language for managing and manipulating data stored in MySQL databases.

❓ What is the most used SQL command?
✅ SELECT is the most commonly used command for retrieving data.

❓ What is the difference between WHERE and HAVING?
✅ WHERE filters rows before grouping, while HAVING filters after aggregation.

❓ Can I use logical and comparison operators together?
✅ Yes, for example: WHERE price > 100 AND category IN ('Books', 'Electronics')

❓ What are aggregate functions used for?
✅ They compute summary values like totals, averages, or counts from a column.

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