Final project submission - (Anuska08 & anuskajena25@gmail.com)

biryani.sql

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+-- Biryani Database Query Exercises Solutions
+-- Project 3 - Complete SQL Query Solutions
+
+-- ==============================================
+-- EASY QUERIES
+-- ==============================================
+
+-- 1a. Retrieve each variety's biryani_id, name, region, and whether it's vegetarian
+SELECT biryani_id, name, region, vegetarian
+FROM BiryaniVarieties;
+
+-- 1b. Spicy non-veg biryanis: Find the name and spice_level of all biryanis where vegetarian = FALSE and spice_level >= 7
+SELECT name, spice_level
+FROM BiryaniVarieties
+WHERE vegetarian = FALSE AND spice_level >= 7;
+
+-- 1c. Available menu items: Show each restaurant's name and the name of biryanis they offer where available = TRUE
+SELECT R.name AS restaurant_name, B.name AS biryani_name
+FROM Restaurants R
+JOIN Menu M ON R.restaurant_id = M.restaurant_id
+JOIN BiryaniVarieties B ON M.biryani_id = B.biryani_id
+WHERE M.available = TRUE;
+
+-- ==============================================
+-- MEDIUM QUERIES
+-- ==============================================
+
+-- 2a. For each biryani variety, count how many distinct ingredients it uses
+SELECT B.biryani_id, B.name, COUNT(DISTINCT R.ingredient_id) AS ingredient_count
+FROM BiryaniVarieties B
+JOIN Recipes R ON B.biryani_id = R.biryani_id
+GROUP BY B.biryani_id, B.name
+ORDER BY ingredient_count DESC;
+
+-- 2b. Calculate total quantity_sold and total total_amount for each biryani across all restaurants
+SELECT B.biryani_id, B.name, 
+       SUM(S.quantity_sold) AS total_quantity_sold,
+       SUM(S.total_amount) AS total_amount
+FROM BiryaniVarieties B
+JOIN Sales S ON B.biryani_id = S.biryani_id
+GROUP BY B.biryani_id, B.name
+ORDER BY total_quantity_sold DESC;
+
+-- 2c. For each restaurant, compute the average rating from Reviews, show only those with average >= 4
+SELECT R.restaurant_id, R.name, AVG(Rev.rating) AS avg_rating
+FROM Restaurants R
+JOIN Reviews Rev ON R.restaurant_id = Rev.restaurant_id
+GROUP BY R.restaurant_id, R.name
+HAVING AVG(Rev.rating) >= 4
+ORDER BY avg_rating DESC;
+
+-- 2d. List all biryani varieties (name) that include at least one allergen ingredient
+SELECT DISTINCT B.name
+FROM BiryaniVarieties B
+JOIN Recipes R ON B.biryani_id = R.biryani_id
+JOIN Ingredients I ON R.ingredient_id = I.ingredient_id
+WHERE I.is_allergen = TRUE
+ORDER BY B.name;
+
+-- ==============================================
+-- HARD QUERIES
+-- ==============================================
+
+-- 3a. For each month in 2025, find the biryani with the highest quantity_sold
+WITH MonthlySales AS (
+    SELECT 
+        EXTRACT(MONTH FROM S.sale_date) AS month_num,
+        MONTHNAME(S.sale_date) AS month_name,
+        B.biryani_id,
+        B.name,
+        SUM(S.quantity_sold) AS monthly_quantity
+    FROM Sales S
+    JOIN BiryaniVarieties B ON S.biryani_id = B.biryani_id
+    WHERE EXTRACT(YEAR FROM S.sale_date) = 2025
+    GROUP BY EXTRACT(MONTH FROM S.sale_date), MONTHNAME(S.sale_date), B.biryani_id, B.name
+),
+RankedSales AS (
+    SELECT 
+        month_num,
+        month_name,
+        biryani_id,
+        name,
+        monthly_quantity,
+        RANK() OVER (PARTITION BY month_num ORDER BY monthly_quantity DESC) AS rank_num
+    FROM MonthlySales
+)
+SELECT month_name, biryani_id, name, monthly_quantity
+FROM RankedSales
+WHERE rank_num = 1
+ORDER BY month_num;
+
+-- 3b. Identify menu entries where average sale price differs by more than 10% from listed price
+WITH SaleAverages AS (
+    SELECT 
+        S.restaurant_id,
+        S.biryani_id,
+        AVG(S.total_amount / S.quantity_sold) AS avg_sale_price
+    FROM Sales S
+    GROUP BY S.restaurant_id, S.biryani_id
+)
+SELECT 
+    M.restaurant_id,
+    M.biryani_id,
+    M.price AS menu_price,
+    SA.avg_sale_price,
+    ABS(((SA.avg_sale_price - M.price) / M.price) * 100) AS percentage_difference
+FROM Menu M
+JOIN SaleAverages SA ON M.restaurant_id = SA.restaurant_id AND M.biryani_id = SA.biryani_id
+WHERE ABS(((SA.avg_sale_price - M.price) / M.price) * 100) > 10
+ORDER BY percentage_difference DESC;
+
+-- 3c. Compare average ratings for each biryani between summer (June-August) and winter (December-February) 2025
+WITH SeasonalRatings AS (
+    SELECT 
+        B.biryani_id,
+        B.name,
+        CASE 
+            WHEN EXTRACT(MONTH FROM Rev.review_date) IN (6, 7, 8) THEN 'Summer'
+            WHEN EXTRACT(MONTH FROM Rev.review_date) IN (12, 1, 2) THEN 'Winter'
+            ELSE 'Other'
+        END AS season,
+        Rev.rating
+    FROM BiryaniVarieties B
+    JOIN Reviews Rev ON B.biryani_id = Rev.biryani_id
+    WHERE EXTRACT(YEAR FROM Rev.review_date) = 2025
+    AND EXTRACT(MONTH FROM Rev.review_date) IN (1, 2, 6, 7, 8, 12)
+)
+SELECT 
+    biryani_id,
+    name,
+    AVG(CASE WHEN season = 'Summer' THEN rating END) AS summer_avg_rating,
+    AVG(CASE WHEN season = 'Winter' THEN rating END) AS winter_avg_rating,
+    AVG(CASE WHEN season = 'Summer' THEN rating END) - AVG(CASE WHEN season = 'Winter' THEN rating END) AS rating_difference
+FROM SeasonalRatings
+GROUP BY biryani_id, name
+HAVING AVG(CASE WHEN season = 'Summer' THEN rating END) IS NOT NULL 
+   AND AVG(CASE WHEN season = 'Winter' THEN rating END) IS NOT NULL
+ORDER BY rating_difference DESC;
+
+-- ==============================================
+-- ADDITIONAL UTILITY QUERIES
+-- ==============================================
+
+-- Verify data integrity: Check for any orphaned records
+SELECT 'Orphaned Menu entries' AS issue, COUNT(*) AS count
+FROM Menu M
+LEFT JOIN Restaurants R ON M.restaurant_id = R.restaurant_id
+LEFT JOIN BiryaniVarieties B ON M.biryani_id = B.biryani_id
+WHERE R.restaurant_id IS NULL OR B.biryani_id IS NULL
+
+UNION ALL
+
+SELECT 'Orphaned Recipe entries' AS issue, COUNT(*) AS count
+FROM Recipes R
+LEFT JOIN BiryaniVarieties B ON R.biryani_id = B.biryani_id
+LEFT JOIN Ingredients I ON R.ingredient_id = I.ingredient_id
+WHERE B.biryani_id IS NULL OR I.ingredient_id IS NULL
+
+UNION ALL
+
+SELECT 'Orphaned Review entries' AS issue, COUNT(*) AS count
+FROM Reviews Rev
+LEFT JOIN Restaurants R ON Rev.restaurant_id = R.restaurant_id
+LEFT JOIN BiryaniVarieties B ON Rev.biryani_id = B.biryani_id
+WHERE R.restaurant_id IS NULL OR B.biryani_id IS NULL
+
+UNION ALL
+
+SELECT 'Orphaned Sales entries' AS issue, COUNT(*) AS count
+FROM Sales S
+LEFT JOIN Restaurants R ON S.restaurant_id = R.restaurant_id
+LEFT JOIN BiryaniVarieties B ON S.biryani_id = B.biryani_id
+WHERE R.restaurant_id IS NULL OR B.biryani_id IS NULL;
+
+-- Summary statistics
+SELECT 
+    (SELECT COUNT(*) FROM BiryaniVarieties) AS total_biryani_varieties,
+    (SELECT COUNT(*) FROM Ingredients) AS total_ingredients,
+    (SELECT COUNT(*) FROM Restaurants) AS total_restaurants,
+    (SELECT COUNT(*) FROM Menu) AS total_menu_items,
+    (SELECT COUNT(*) FROM Reviews) AS total_reviews,
+    (SELECT COUNT(*) FROM Sales) AS total_sales_records,
+    (SELECT COUNT(*) FROM Recipes) AS total_recipe_entries;
+
+-- END OF QUERY EXERCISES