Initialize blog and airline databases with sample data

lab.sql

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+-- ============================================================
+-- EXERCISE 1: Blog Database (Normalized to 3NF)
+-- ============================================================
+
+CREATE TABLE authors (
+    id          INT PRIMARY KEY AUTO_INCREMENT,
+    name        VARCHAR(100) NOT NULL UNIQUE
+);
+
+CREATE TABLE posts (
+    id          INT PRIMARY KEY AUTO_INCREMENT,
+    author_id   INT NOT NULL,
+    title       VARCHAR(255) NOT NULL,
+    word_count  INT NOT NULL CHECK (word_count > 0),
+    views       INT NOT NULL DEFAULT 0 CHECK (views >= 0),
+    FOREIGN KEY (author_id) REFERENCES authors(id)
+);
+
+-- Sample Data - Exercise 1
+INSERT INTO authors (name) VALUES
+    ('Maria Charlotte'),
+    ('Juan Perez'),
+    ('Gemma Alcocer');
+
+INSERT INTO posts (author_id, title, word_count, views) VALUES
+    (1, 'Best Paint Colors',           814,  14),
+    (2, 'Small Space Decorating Tips', 1146, 221),
+    (1, 'Hot Accessories',             986,  105),
+    (1, 'Mixing Textures',             765,  22),
+    (2, 'Kitchen Refresh',             1242, 307),
+    (1, 'Homemade Art Hacks',          1002, 193),
+    (3, 'Refinishing Wood Floors',     1571, 7542);
+
+
+-- ============================================================
+-- EXERCISE 2: Airline Database (Normalized to 3NF)
+-- ============================================================
+
+CREATE TABLE aircrafts (
+    id           INT PRIMARY KEY AUTO_INCREMENT,
+    name         VARCHAR(100) NOT NULL UNIQUE,
+    total_seats  INT NOT NULL CHECK (total_seats > 0)
+);
+
+CREATE TABLE flights (
+    flight_number  VARCHAR(10) PRIMARY KEY,
+    aircraft_id    INT NOT NULL,
+    mileage        INT NOT NULL CHECK (mileage > 0),
+    FOREIGN KEY (aircraft_id) REFERENCES aircrafts(id)
+);
+
+CREATE TABLE customers (
+    id              INT PRIMARY KEY AUTO_INCREMENT,
+    name            VARCHAR(100) NOT NULL UNIQUE,
+    status          ENUM('None', 'Silver', 'Gold') NOT NULL DEFAULT 'None',
+    total_mileage   INT NOT NULL DEFAULT 0 CHECK (total_mileage >= 0)
+);
+
+CREATE TABLE bookings (
+    id              INT PRIMARY KEY AUTO_INCREMENT,
+    customer_id     INT NOT NULL,
+    flight_number   VARCHAR(10) NOT NULL,
+    FOREIGN KEY (customer_id) REFERENCES customers(id),
+    FOREIGN KEY (flight_number) REFERENCES flights(flight_number)
+);
+
+-- Sample Data - Exercise 2
+
+INSERT INTO aircrafts (name, total_seats) VALUES
+    ('Boeing 747',  400),
+    ('Airbus A330', 236),
+    ('Boeing 777',  264);
+
+INSERT INTO flights (flight_number, aircraft_id, mileage) VALUES
+    ('DL143', 1, 135),
+    ('DL122', 2, 4370),
+    ('DL53',  3, 2078),
+    ('DL222', 3, 1765),
+    ('DL37',  1, 531);
+
+INSERT INTO customers (name, status, total_mileage) VALUES
+    ('Agustine Riviera', 'Silver', 115235),
+    ('Alaina Sepulvida', 'None',   6008),
+    ('Tom Jones',        'Gold',   205767),
+    ('Sam Rio',          'None',   2653),
+    ('Jessica James',    'Silver', 127656),
+    ('Ana Janco',        'Silver', 136773),
+    ('Jennifer Cortez',  'Gold',   300582),
+    ('Christian Janco',  'Silver', 14642);
+
+INSERT INTO bookings (customer_id, flight_number) VALUES
+    (1, 'DL143'),
+    (1, 'DL122'),
+    (2, 'DL122'),
+    (1, 'DL143'),
+    (3, 'DL122'),
+    (3, 'DL53'),
+    (1, 'DL143'),
+    (4, 'DL143'),
+    (1, 'DL143'),
+    (3, 'DL222'),
+    (5, 'DL143'),
+    (4, 'DL143'),
+    (6, 'DL222'),
+    (7, 'DL222'),
+    (5, 'DL122'),
+    (4, 'DL37'),
+    (8, 'DL222');
+
+
+-- ============================================================
+-- EXERCISE 3: SQL Queries on the Airline Database
+-- ============================================================
+
+-- 1. Total number of flights
+SELECT COUNT(DISTINCT flight_number) AS total_flights
+FROM flights;
+
+-- 2. Average flight distance
+SELECT AVG(mileage) AS avg_flight_distance
+FROM flights;
+
+-- 3. Average number of seats per aircraft
+SELECT AVG(total_seats) AS avg_seats_per_aircraft
+FROM aircrafts;
+
+-- 4. Average miles flown by customers, grouped by status
+SELECT status, AVG(total_mileage) AS avg_mileage
+FROM customers
+GROUP BY status;
+
+-- 5. Max miles flown by customers, grouped by status
+SELECT status, MAX(total_mileage) AS max_mileage
+FROM customers
+GROUP BY status;
+
+-- 6. Number of aircrafts with "Boeing" in their name
+SELECT COUNT(*) AS boeing_count
+FROM aircrafts
+WHERE name LIKE '%Boeing%';
+
+-- 7. Flights with distance between 300 and 2000 miles
+SELECT *
+FROM flights
+WHERE mileage BETWEEN 300 AND 2000;
+
+-- 8. Average flight distance booked, grouped by customer status
+SELECT c.status, AVG(f.mileage) AS avg_booked_distance
+FROM bookings b
+JOIN customers c ON b.customer_id = c.id
+JOIN flights f   ON b.flight_number = f.flight_number
+GROUP BY c.status;
+
+-- 9. Most booked aircraft among Gold status members
+SELECT a.name, COUNT(*) AS total_bookings
+FROM bookings b
+JOIN customers c ON b.customer_id = c.id
+JOIN flights f   ON b.flight_number = f.flight_number
+JOIN aircrafts a ON f.aircraft_id = a.id
+WHERE c.status = 'Gold'
+GROUP BY a.name
+ORDER BY total_bookings DESC
+LIMIT 1;