Solved lab

lab-sql-aggregation.sql

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+-- Challenge 1
+
+-- 1.1 Shortest and longest movie durations
+SELECT
+  MAX(length) AS max_duration,
+  MIN(length) AS min_duration
+FROM film;
+
+-- 1.2 Average movie duration as H and M (no decimals)
+SELECT
+  CONCAT(
+    FLOOR(AVG(length)/60), 'h ',
+    MOD(FLOOR(AVG(length)), 60), 'm'
+  ) AS avg_duration_hm
+FROM film;
+
+-- 2.1 Days the company has been operating
+SELECT
+  DATEDIFF(MAX(rental_date), MIN(rental_date)) AS days_operating
+FROM rental;
+
+-- 2.2 Rental info + month and weekday (20 rows)
+SELECT
+  rental_id, rental_date, return_date, customer_id, staff_id,
+  MONTHNAME(rental_date) AS rental_month,
+  DAYNAME(rental_date)   AS rental_weekday
+FROM rental
+ORDER BY rental_date
+LIMIT 20;
+
+-- 2.3 BONUS: Rental info + DAY_TYPE = weekend/workday (20 rows)
+SELECT
+  rental_id, rental_date, return_date, customer_id, staff_id,
+  CASE
+    WHEN DAYOFWEEK(rental_date) IN (1,7) THEN 'weekend'
+    ELSE 'workday'
+  END AS day_type
+FROM rental
+ORDER BY rental_date
+LIMIT 20;
+
+-- 3. Film titles + rental_duration, NULL -> 'Not Available'
+SELECT
+  title,
+  IFNULL(CAST(rental_duration AS CHAR), 'Not Available') AS rental_duration
+FROM film
+ORDER BY title ASC;
+
+-- BONUS: Full name + first 3 chars of email, ordered by last name
+SELECT
+  CONCAT(first_name, ' ', last_name) AS full_name,
+  SUBSTRING(email, 1, 3)            AS email_prefix
+FROM customer
+ORDER BY last_name ASC;
+
+
+
+-- Challenge 2
+
+-- 1.1 Total number of films released
+SELECT COUNT(*) AS total_films FROM film;
+
+-- 1.2 Number of films for each rating
+SELECT
+  rating,
+  COUNT(*) AS film_count
+FROM film
+GROUP BY rating;
+
+-- 1.3 Number of films per rating, descending by count
+SELECT
+  rating,
+  COUNT(*) AS film_count
+FROM film
+GROUP BY rating
+ORDER BY film_count DESC;
+
+-- 2.1 Mean film duration by rating (rounded to 2 decimals), desc
+SELECT
+  rating,
+  ROUND(AVG(length), 2) AS avg_length
+FROM film
+GROUP BY rating
+ORDER BY avg_length DESC;
+
+-- 2.2 Ratings with mean duration > 2 hours
+SELECT
+  rating,
+  ROUND(AVG(length), 2) AS avg_length
+FROM film
+GROUP BY rating
+HAVING AVG(length) > 120
+ORDER BY avg_length DESC;
+
+-- BONUS: Last names in actor table that are NOT repeated
+SELECT
+  last_name
+FROM actor
+GROUP BY last_name
+HAVING COUNT(*) = 1
+ORDER BY last_name;