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Quick Start

Quick Start

Learn essential SQL operations and query patterns for effective database work. This Quick Start teaches core SQL concepts applicable to all SQL databases.

🎯 What You’ll Learn

By the end of this tutorial, you’ll understand:

  • SELECT queries with filtering and sorting
  • Joins and relationships
  • Aggregate functions and grouping
  • Subqueries and advanced patterns

📋 Prerequisites

  • SQLite installed (see Initial Setup)
  • Basic understanding of relational databases

📊 SELECT Queries

Basic SELECT 

SELECT * FROM users;
SELECT name, email FROM users;
SELECT DISTINCT email FROM users;

Filtering with WHERE 

SELECT * FROM users WHERE age > 25;
SELECT * FROM users WHERE name LIKE 'A%';
SELECT * FROM users WHERE email = 'alice@example.com';
SELECT * FROM users WHERE age BETWEEN 20 AND 30;
SELECT * FROM users WHERE name IN ('Alice', 'Bob', 'Charlie');

Sorting with ORDER BY 

SELECT * FROM users ORDER BY name;
SELECT * FROM users ORDER BY created_at DESC;
SELECT * FROM users ORDER BY age DESC, name ASC;

Limiting Results 

SELECT * FROM users LIMIT 10;
SELECT * FROM users LIMIT 10 OFFSET 20;

🔗 Joins

INNER JOIN 

SELECT users.name, posts.title
FROM users
INNER JOIN posts ON users.id = posts.user_id;

LEFT JOIN 

SELECT users.name, posts.title
FROM users
LEFT JOIN posts ON users.id = posts.user_id;

RIGHT JOIN 

SELECT users.name, posts.title
FROM users
RIGHT JOIN posts ON users.id = posts.user_id;

📈 Aggregate Functions 

SELECT COUNT(*) FROM users;
SELECT AVG(age) FROM users;
SELECT MAX(age), MIN(age) FROM users;
SELECT SUM(price) FROM orders;

GROUP BY 

SELECT user_id, COUNT(*) as post_count
FROM posts
GROUP BY user_id;

SELECT user_id, COUNT(*) as post_count
FROM posts
GROUP BY user_id
HAVING COUNT(*) > 5;

🎨 Subqueries 

SELECT * FROM users
WHERE id IN (SELECT DISTINCT user_id FROM posts);

SELECT name FROM users
WHERE id = (SELECT user_id FROM posts WHERE title = 'First Post');

✅ Next Steps

You now understand SQL essentials! To deepen your knowledge:

  1. Try the examples: Execute each SQL statement
  2. Explore By Example: SQL By Example

🎯 Self-Assessment

After completing this Quick Start, you should be able to:

  • Write SELECT queries with filtering
  • Use JOIN operations
  • Apply aggregate functions
  • Group and filter results
  • Write subqueries
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Initial Setup