-- Simple function
CREATE OR REPLACE FUNCTION get_full_name(
  first_name VARCHAR,
  last_name VARCHAR
)
RETURNS VARCHAR AS $$

-- Unnormalized (0NF): Repeating groups
CREATE TABLE orders_bad (
  order_id INT,
  customer_name VARCHAR(100),
  customer_email VARCHAR(100),
  product1 VARCHAR(100),

-- Basic transaction
BEGIN;

UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;

-- Basic EXPLAIN
EXPLAIN
SELECT * FROM users WHERE email = 'alice@example.com';

-- EXPLAIN with cost and row estimates
-- Output shows: Seq Scan on users (cost=0.00..15.50 rows=1 width=100)

-- Create table with JSONB column
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  email VARCHAR(255) NOT NULL,
  name VARCHAR(255),
  metadata JSONB DEFAULT '{}'::jsonb

-- Basic CTE
WITH high_value_customers AS (
  SELECT
    user_id,
    SUM(total) as lifetime_value
  FROM orders

-- ROW_NUMBER: Unique sequential number
SELECT
  name,
  department,
  salary,
  ROW_NUMBER() OVER (ORDER BY salary DESC) as overall_rank,

-- Create basic index
CREATE INDEX idx_users_email ON users(email);

-- Unique index (enforces uniqueness)
CREATE UNIQUE INDEX idx_users_username ON users(username);

-- INNER JOIN: Only matching rows
SELECT
  users.name,
  orders.order_number,
  orders.total
FROM users

# Gemfile
gem 'dry-types'
gem 'dry-struct'

require 'dry-types'
require 'dry-struct'

# Define refinements in a module
module StringExtensions
  refine String do
    def titleize
      split.map(&:capitalize).join(' ')
    end

# Basic Ractor usage
ractor = Ractor.new do
  # This runs in parallel, isolated from main thread
  result = heavy_computation
  result
end