"Solved lab"

lab_Aggregation_transformation.sql

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+use sakila;
+
+
+-- CHALLENGE 1
+
+-- 1.1
+
+SELECT 
+  MAX(length) AS max_duration,
+  MIN(length) AS min_duration
+FROM film;
+
+
+
+-- 1.2
+
+WITH avg_len AS (
+  SELECT AVG(length) AS m 
+  FROM film
+)
+SELECT
+  FLOOR(m/60) + IF(ROUND(MOD(m,60)) = 60, 1, 0) AS avg_hours,
+  IF(ROUND(MOD(m,60)) = 60, 0, ROUND(MOD(m,60))) AS avg_minutes
+FROM avg_len;
+
+
+
+-- 2.1
+
+SELECT 
+  DATEDIFF(MAX(rental_date), MIN(rental_date)) + 1 AS operating_days
+FROM rental;
+
+
+-- 2.2
+
+SELECT
+  rental_id,
+  rental_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)
+
+SELECT
+  rental_id,
+  rental_date,
+  customer_id,
+  staff_id,
+  MONTHNAME(rental_date) AS rental_month,
+  DAYNAME(rental_date)   AS rental_weekday,
+  CASE 
+    WHEN DAYOFWEEK(rental_date) IN (1, 7) THEN 'weekend'  -- 1=Sun, 7=Sat
+    ELSE 'workday'
+  END AS DAY_TYPE
+FROM rental
+ORDER BY rental_date
+LIMIT 20;
+
+
+-- 3
+
+SELECT 
+  title,
+  IFNULL(CAST(rental_duration AS CHAR), 'Not Available') AS rental_duration
+FROM film
+ORDER BY title ASC;
+
+
+-- 4 
+
+SELECT
+  CONCAT(first_name, ' ', last_name) AS full_name,
+  LEFT(IFNULL(email, ''), 3)         AS email_prefix
+FROM customer
+ORDER BY last_name ASC, first_name ASC;
+
+
+-- CHALLENGE 2
+
+-- 1.1
+
+SELECT COUNT(*) AS total_films
+FROM film;
+
+
+-- 1.2 
+
+SELECT 
+  rating,
+  COUNT(*) AS film_count
+FROM film
+GROUP BY rating;
+
+
+-- 1.3
+
+SELECT 
+  rating,
+  COUNT(*) AS film_count
+FROM film
+GROUP BY rating
+ORDER BY film_count DESC;
+
+
+-- 2.1
+
+SELECT 
+  rating,
+  ROUND(AVG(length), 2) AS avg_duration
+FROM film
+GROUP BY rating
+ORDER BY avg_duration DESC;
+
+
+
+-- 2.2 
+SELECT 
+  rating,
+  ROUND(AVG(length), 2) AS avg_duration
+FROM film
+GROUP BY rating
+HAVING AVG(length) > 120
+ORDER BY avg_duration DESC;
+
+-- 3 BONUS 
+
+SELECT last_name
+FROM actor
+GROUP BY last_name
+HAVING COUNT(*) = 1
+ORDER BY last_name ASC;