Assignment two

02_activities/assignments/Assignment2.md

@@ -55,6 +55,27 @@ The store wants to keep customer addresses. Propose two architectures for the CU
 
 ```
 Your answer...
+
+Option 1 – Overwrite
+
+One record per customer in CUSTOMER_ADDRESS.
+
+When a customer changes their address, the row is updated with the new information.
+
+No history of previous addresses is kept.
+
+This is Type 1 Slowly Changing Dimension 
+
+Option 2 – Retain Changes (History)
+
+Multiple records per customer in CUSTOMER_ADDRESS.
+
+Each address has start_date and end_date columns.
+
+When a customer moves, a new record is inserted with the new address, and the old record is marked inactive by setting end_date.
+
+This is Type 2 Slowly Changing Dimension.
+
 ```
 
 ***

02_activities/assignments/assignment2.sql

@@ -19,6 +19,12 @@ HINT: keep the syntax the same, but edited the correct components with the strin
 The `||` values concatenate the columns into strings. 
 Edit the appropriate columns -- you're making two edits -- and the NULL rows will be fixed. 
 All the other rows will remain the same.) */
+SELECT 
+product_name || ', ' || COALESCE(product_size,'') || ' (' || COALESCE(product_qty_type,'') || ')'
+FROM product;
+SELECT 
+product_name || ', ' || COALESCE(product_size,'unit') || ' (' || COALESCE(product_qty_type,'unit') || ')'
+FROM product;
 
 
 
@@ -32,17 +38,41 @@ each new market date for each customer, or select only the unique market dates p
 (without purchase details) and number those visits. 
 HINT: One of these approaches uses ROW_NUMBER() and one uses DENSE_RANK(). */
 
+SELECT 
+    customer_id,
+    market_date,
+    ROW_NUMBER() OVER(PARTITION BY customer_id ORDER BY market_date) AS visit_number
+FROM customer_purchases;
 
 
 /* 2. Reverse the numbering of the query from a part so each customer’s most recent visit is labeled 1, 
 then write another query that uses this one as a subquery (or temp table) and filters the results to 
 only the customer’s most recent visit. */
 
+SELECT *
+FROM (
+SELECT 
+ customer_id,
+ market_date,
+ ROW_NUMBER() OVER(PARTITION BY customer_id ORDER BY market_date DESC) AS visit_number
+ FROM customer_purchases
+) sub
+WHERE visit_number = 1;
+
+
 
 
 /* 3. Using a COUNT() window function, include a value along with each row of the 
 customer_purchases table that indicates how many different times that customer has purchased that product_id. */
 
+SELECT 
+customer_id,
+product_id,
+market_date,
+quantity,
+cost_to_customer_per_qty,
+COUNT(*) OVER(PARTITION BY customer_id, product_id) AS times_purchased
+FROM customer_purchases;
 
 
 -- String manipulations
@@ -57,10 +87,24 @@ Remove any trailing or leading whitespaces. Don't just use a case statement for
 
 Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR will help split the column. */
 
+SELECT 
+    product_name,
+
+    TRIM(
+        SUBSTR(
+            product_name, 
+            INSTR(product_name,'-') + 1  
+        )
+    ) AS description
+FROM product
+WHERE INSTR(product_name,'-') > 0;
 
 
 /* 2. Filter the query to show any product_size value that contain a number with REGEXP. */
 
+SELECT *
+FROM product
+WHERE product_size REGEXP '[0-9]';
 
 
 -- UNION
@@ -73,6 +117,36 @@ HINT: There are a possibly a few ways to do this query, but if you're struggling
 3) Query the second temp table twice, once for the best day, once for the worst day, 
 with a UNION binding them. */
 
+--Aggregate total sales per date
+WITH sales_per_day AS (
+    SELECT 
+        market_date,
+        SUM(quantity * cost_to_customer_per_qty) AS total_sales
+    FROM customer_purchases
+    GROUP BY market_date
+)
+
+--Rank the dates by total sales
+, ranked_sales AS (
+    SELECT 
+        market_date,
+        total_sales,
+        RANK() OVER(ORDER BY total_sales DESC) AS rank_high,  -- highest sales
+        RANK() OVER(ORDER BY total_sales ASC) AS rank_low     -- lowest sales
+    FROM sales_per_day
+)
+
+--Select best and worst days
+SELECT 'Best Day' AS label, market_date, total_sales
+FROM ranked_sales
+WHERE rank_high = 1
+
+UNION
+
+SELECT 'Worst Day' AS label, market_date, total_sales
+FROM ranked_sales
+WHERE rank_low = 1;
+
 
 
 
@@ -89,6 +163,26 @@ Think a bit about the row counts: how many distinct vendors, product names are t
 How many customers are there (y). 
 Before your final group by you should have the product of those two queries (x*y).  */
 
+SELECT 
+    v.vendor_name,
+    p.product_name,
+    SUM(5 * vi.original_price) AS potential_revenue
+FROM 
+    (SELECT DISTINCT vendor_id, vendor_name FROM vendor) v
+CROSS JOIN 
+    (SELECT DISTINCT customer_id FROM customer) c  
+JOIN 
+    vendor_inventory vi
+    ON vi.vendor_id = v.vendor_id
+JOIN 
+    product p
+    ON p.product_id = vi.product_id
+GROUP BY 
+    v.vendor_name,
+    p.product_name
+ORDER BY 
+    v.vendor_name,
+    p.product_name;
 
 
 -- INSERT
@@ -98,17 +192,50 @@ It should use all of the columns from the product table, as well as a new column
 Name the timestamp column `snapshot_timestamp`. */
 
 
+DROP TABLE IF EXISTS product_units;
+
+CREATE TABLE product_units AS
+SELECT
+    *,
+    CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
+
+SELECT * FROM product_units;
+
+
+
+
+
 
 /*2. Using `INSERT`, add a new row to the product_units table (with an updated timestamp). 
 This can be any product you desire (e.g. add another record for Apple Pie). */
 
+INSERT INTO product_units (product_id, product_name, product_size, product_category_id, product_qty_type, snapshot_timestamp)
+VALUES (
+    1000,                     -- new product_id
+    'Apple Pie',             -- product_name
+    '1 unit',                -- product_size
+	100,                     --product_category_id
+    'unit',                  -- product_qty_type
+    CURRENT_TIMESTAMP        -- snapshot_timestamp
+);
 
+--SELECT * FROM product_units
+--WHERE product_id = 1000;
 
 -- DELETE
 /* 1. Delete the older record for the whatever product you added. 
 
 HINT: If you don't specify a WHERE clause, you are going to have a bad time.*/
 
+DELETE FROM product_units
+WHERE product_name = 'Apple Pie'
+ AND snapshot_timestamp < (
+ SELECT MAX(snapshot_timestamp)
+ FROM product_units
+ WHERE product_name = 'Apple Pie'
+  );
 
 
 -- UPDATE
@@ -128,6 +255,32 @@ Finally, make sure you have a WHERE statement to update the right row,
 	you'll need to use product_units.product_id to refer to the correct row within the product_units table. 
 When you have all of these components, you can run the update statement. */
 
-
+ALTER TABLE product_units
+ADD COLUMN current_quantity INT;
+
+SELECT vi.product_id, vi.quantity
+FROM vendor_inventory vi
+INNER JOIN (
+SELECT product_id, MAX(market_date) AS last_date
+FROM vendor_inventory
+GROUP BY product_id
+) latest
+ON vi.product_id = latest.product_id AND vi.market_date = latest.last_date;
+
+
+UPDATE product_units
+SET current_quantity = COALESCE((
+SELECT vi.quantity
+FROM vendor_inventory vi
+INNER JOIN (
+SELECT product_id, MAX(market_date) AS last_date
+FROM vendor_inventory
+GROUP BY product_id
+    ) latest
+ON vi.product_id = latest.product_id AND vi.market_date = latest.last_date
+WHERE vi.product_id = product_units.product_id
+), 0);
+
+SELECT * FROM product_units