/* Static positioning (default) */
.static {
position: static; /* Normal document flow */
}
/* Relative positioning *//* Basic grid container */
.grid-container {
display: grid;
/* Define columns: 3 equal columns */
grid-template-columns: 1fr 1fr 1fr;/* Basic flexbox container */
.flex-container {
display: flex;
/* flex-direction: row | row-reverse | column | column-reverse */
flex-direction: row; /* default */<!DOCTYPE html>
<html lang="en">
<head>
<!-- Essential meta tags -->
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Form Validation Example</title>
<style><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Semantic HTML Example</title>-- Basic query debugging with EXPLAIN
EXPLAIN SELECT * FROM users WHERE email = 'test@example.com';
-- Output shows query plan:
-- Seq Scan on users (cost=0.00..25.00 rows=1 width=100)
-- Filter: (email = 'test@example.com'::text)-- SCHEMA DESIGN CHECKLIST
-- 1. Use appropriate data types
CREATE TABLE users_optimized (
id SERIAL PRIMARY KEY, -- Auto-increment
uuid UUID DEFAULT gen_random_uuid(), -- UUID for external IDs-- Prepared statements basics
-- PostgreSQL syntax
PREPARE get_user (INT) AS
SELECT id, username, email
FROM users
WHERE id = $1;-- Pattern: Single Table Inheritance (STI)
CREATE TABLE users (
id SERIAL PRIMARY KEY,
type VARCHAR(50) NOT NULL, -- 'admin', 'customer', 'vendor'
username VARCHAR(100) UNIQUE NOT NULL,
email VARCHAR(100) UNIQUE NOT NULL,-- Row-level locks with SELECT FOR UPDATE
BEGIN;
SELECT * FROM inventory
WHERE product_id = 123
FOR UPDATE; -- Locks selected rows-- Create test database
CREATE DATABASE myapp_test;
-- Test isolation with transactions
/*
beforeEach(async () => {