Assignment two

02_activities/assignments/Assignment2.md

@@ -32,6 +32,7 @@ Steps to complete this part of the assignment:
 - Write, within this markdown file, an answer to Prompt 3
 
 
+
 ###  Design a Logical Model
 
 #### Prompt 1
@@ -43,7 +44,12 @@ Additionally, include a date table.
 
 There are several tools online you can use, I'd recommend [Draw.io](https://www.drawio.com/) or [LucidChart](https://www.lucidchart.com/pages/).
 
+
+**HINT:** You do not need to create any data for this prompt. This is a logical model (ERD) only. 
+
 **HINT:** You do not need to create any data for this prompt. This is a conceptual model only. 
+# Created base bookstore schema with core tables
+
 
 #### Prompt 2
 We want to create employee shifts, splitting up the day into morning and evening. Add this to the ERD.
@@ -57,7 +63,9 @@ The store wants to keep customer addresses. Propose two architectures for the CU
 Your answer...
 ```
 
-***
+# The Type 1 architecture is where the CUSTOMER_ADDRESS simply overwrites old information when a customer's address changes. This saves storage space but loses historical data.
+
+# The Type 2 architecture is the model where the CUSTOMER_ADDRESS table retains historical address changes by creating new records with effective_date, end_date, and an is_current flag. This method preserves historical data, allowing us to know past addresses, but it requires more storage and slightly more complex queries (for example, finding the current address where is_current = TRUE or end_date IS NULL).
 
 ## Section 2:
 You can start this section following *session 4*.

02_activities/assignments/assignment2-db browser.sql

@@ -0,0 +1,180 @@
+--COALESCE
+SELECT 
+  product_name || ', ' || COALESCE(product_size, '') || ' (' || COALESCE(product_qty_type, 'unit') || ')' AS product_full_description
+FROM product;
+
+--Windowed Functions
+--Q1
+SELECT 
+  customer_id,
+  market_date,
+  ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date) AS visit_number
+FROM customer_purchases;
+
+SELECT 
+  customer_id, 
+  market_date,
+  DENSE_RANK() OVER (PARTITION BY customer_id ORDER BY market_date) AS visit_number
+FROM customer_purchases;
+
+--Q2
+WITH visit_ranking AS (
+  SELECT 
+    customer_id,
+    market_date,
+    ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date DESC) AS rn
+  FROM customer_purchases
+)
+SELECT 
+  customer_id,
+  market_date
+FROM visit_ranking
+WHERE rn = 1;
+
+SELECT 
+  customer_id,
+  product_id,
+  COUNT(*) OVER (PARTITION BY customer_id, product_id) AS purchase_count
+FROM customer_purchases;
+
+--String manipulation
+SELECT 
+  product_name,
+  CASE 
+    WHEN INSTR(product_name, '-') > 0 THEN TRIM(SUBSTR(product_name, INSTR(product_name, '-') + 1))
+    ELSE NULL
+  END AS description
+FROM product;
+
+SELECT 
+  product_name,
+  product_size
+FROM product
+WHERE product_size REGEXP '[0-9]';
+
+-- UNION
+WITH daily_sales AS (
+  SELECT 
+    market_date,
+    SUM(quantity * cost_to_customer_per_qty) AS total_sales
+  FROM customer_purchases
+  GROUP BY market_date
+),
+ranked_sales AS (
+  SELECT 
+    market_date,
+    total_sales,
+    RANK() OVER (ORDER BY total_sales DESC) AS sales_rank_high,
+    RANK() OVER (ORDER BY total_sales ASC) AS sales_rank_low
+  FROM daily_sales
+)
+
+SELECT market_date, total_sales, 'Highest Sales' AS sales_type
+FROM ranked_sales
+WHERE sales_rank_high = 1
+
+UNION
+
+SELECT market_date, total_sales, 'Lowest Sales' AS sales_type
+FROM ranked_sales
+WHERE sales_rank_low = 1
+
+ORDER BY total_sales DESC;
+
+
+
+-- Cross Join
+WITH product_vendor_info AS (
+    SELECT
+        v.vendor_name,
+        p.product_name,
+        p.product_id,
+        vi.vendor_id,
+        vi.original_price AS product_price
+    FROM vendor_inventory vi
+    JOIN product p ON vi.product_id = p.product_id
+    JOIN vendor v ON vi.vendor_id = v.vendor_id
+),
+cross_joined_sales AS (
+    SELECT
+        pvi.vendor_name,
+        pvi.product_name,
+        pvi.product_price,
+        c.customer_id,
+        5 AS quantity -- Each customer buys 5 of each product
+    FROM product_vendor_info pvi
+    CROSS JOIN customer c
+)
+
+SELECT
+    vendor_name,
+    product_name,
+    SUM(quantity * product_price) AS potential_revenue
+FROM cross_joined_sales
+GROUP BY vendor_name, product_name
+ORDER BY vendor_name, product_name;
+
+
+-- First drop table if it exists to avoid errors
+DROP TABLE IF EXISTS product_units;
+
+-- Then create the table
+CREATE TABLE product_units AS
+SELECT 
+    product_id,
+    product_name, 
+    product_size,
+    product_category_id,
+    product_qty_type,
+    CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM 
+    product
+WHERE 
+    product_qty_type = 'unit';
+
+-- 2. Insert a new unit product with current timestamp
+INSERT INTO product_units (
+    product_id,
+    product_name,
+    product_size,
+    product_category_id,
+    product_qty_type,
+    snapshot_timestamp
+)
+VALUES (
+    (SELECT COALESCE(MAX(product_id), 0) + 1 FROM product_units), -- Auto-increment ID
+    'Gourmet Apple Pie', -- New product name
+    '10 inch', -- Product size
+    (SELECT product_category_id FROM product WHERE product_name LIKE '%Pie%' LIMIT 1), -- Matching category
+    'unit', -- Quantity type
+    CURRENT_TIMESTAMP -- Current timestamp
+);
+
+-- DELETE
+/* 1. Delete the older record for the whatever product you added. */
+DELETE FROM product_units
+WHERE product_id = (
+    SELECT product_id 
+    FROM product_units 
+    WHERE product_name = 'Gourmet Apple Pie'
+    ORDER BY snapshot_timestamp ASC
+    LIMIT 1
+);
+
+-- UPDATE
+/* 1. Add current_quantity to product_units and update with last quantity from vendor_inventory */
+
+-- First add the column
+ALTER TABLE product_units
+ADD current_quantity INT;
+
+-- Then update with the last quantity values
+UPDATE product_units
+SET current_quantity = COALESCE(
+    (SELECT quantity 
+     FROM vendor_inventory vi 
+     WHERE vi.product_id = product_units.product_id
+     ORDER BY market_date DESC, vendor_id DESC
+     LIMIT 1),
+    0
+);