SQL Online Editor

Let's start with basic SQL queries:

-- Basic SELECT statement
SELECT * FROM users;

-- Filtering with WHERE
SELECT name, email
FROM users
WHERE age > 21;

-- Sorting results
SELECT name, created_at
FROM users
ORDER BY created_at DESC;

Use our sample databases to practice different queries. The editor provides syntax highlighting and immediate feedback on query results.

Learn table creation and modification:

-- Create a new table
CREATE TABLE users (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT UNIQUE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Insert data
INSERT INTO users (name, email) VALUES
    ('John Doe', 'john@email.com'),
    ('Jane Smith', 'jane@email.com');

-- Modify table structure
ALTER TABLE users
ADD COLUMN age INTEGER;

Practice these commands in our editor with immediate results.

Explore different types of joins:

-- INNER JOIN example
SELECT orders.id, users.name
FROM orders
INNER JOIN users ON orders.user_id = users.id;

-- LEFT JOIN example
SELECT users.name, orders.id
FROM users
LEFT JOIN orders ON users.id = orders.user_id;

-- Multiple joins
SELECT orders.id, users.name, products.title
FROM orders
JOIN users ON orders.user_id = users.id
JOIN products ON orders.product_id = products.id;

Experiment with different join types in our editor.

Master aggregate functions and grouping:

-- Basic aggregations
SELECT 
    COUNT(*) as total_users,
    AVG(age) as average_age,
    MAX(salary) as highest_salary
FROM users;

-- Grouping results
SELECT 
    country,
    COUNT(*) as user_count,
    AVG(age) as avg_age
FROM users
GROUP BY country;

-- Using HAVING
SELECT 
    department,
    AVG(salary) as avg_salary
FROM employees
GROUP BY department
HAVING AVG(salary) > 50000;

Practice these aggregate functions in our editor.

Learn query optimization techniques:

-- Create an index
CREATE INDEX idx_email ON users(email);

-- Use specific columns instead of SELECT *
SELECT id, name, email
FROM users
WHERE email LIKE '%@company.com';

-- Analyze query performance
EXPLAIN QUERY PLAN
SELECT *
FROM users
WHERE email = 'test@example.com';

Our editor helps you practice writing efficient queries with real-time execution feedback.

Learn transaction management:

-- Start a transaction
BEGIN TRANSACTION;

-- Withdraw from first account
UPDATE accounts
SET balance = balance - 100
WHERE id = 1;

-- Deposit to second account
UPDATE accounts
SET balance = balance + 100
WHERE id = 2;

-- If everything is OK, commit the transaction
COMMIT;

-- If there's an error, rollback
-- ROLLBACK;

Practice transaction management in our safe, sandboxed environment.

Explore these official resources and learning materials:

Official Documentation:

• SQL Standard (ISO/IEC 9075) - Official SQL specification
• SQLite Documentation - Complete SQLite reference
• SQLite Language Reference - SQL syntax and commands
• SQLite Tutorial - Official getting started guide

Learning Resources:

• W3Schools SQL Tutorial - Comprehensive SQL learning
• SQL Style Guide - Writing clean SQL code
• Database Design Fundamentals - Schema design principles
• SQL Best Practices - Query optimization

Advanced Topics:

• SQLite Performance Tuning - Optimization techniques
• Database Normalization - Schema design theory
• SQL Injection Prevention - Security best practices

These resources cover SQL from basic queries to advanced database design and optimization!