Assignment-2

02_activities/assignments/Microcredential_Cohort/Assignment2.md

@@ -58,6 +58,30 @@ The store wants to keep customer addresses. Propose two architectures for the CU
 ```
 Your answer...
 ```
+Architecture 1 — Overwrite the Address (SCD Type 1)
+
+CUSTOMER_ADDRESS (Type 1) --> This design keeps only the current address.If a customer moves, the old address is lost.
+customer_id (PK, FK → CUSTOMER)
+street
+city
+province
+postal_code
+country
+
+
+Architecture 2 — Retain Address History (SCD Type 2):
+CUSTOMER_ADDRESS (Type 2) --> This design keeps every version of a customer’s address over time
+customer_address_id (PK)
+customer_id (FK → CUSTOMER)
+street
+city
+province
+postal_code
+country
+start_date
+end_date
+is_current
+
 
 ***
 

02_activities/assignments/Microcredential_Cohort/assignment2.sql

@@ -23,8 +23,9 @@ Edit the appropriate columns -- you're making two edits -- and the NULL rows wil
 All the other rows will remain the same. */
 --QUERY 1
 
-
-
+SELECT 
+product_name || ', ' || COALESCE(product_size,'')|| ' (' || COALESCE(product_qty_type, 'unit') || ')' AS list_of_products
+FROM product;
 
 --END QUERY
 
@@ -41,8 +42,32 @@ HINT: One of these approaches uses ROW_NUMBER() and one uses DENSE_RANK().
 Filter the visits to dates before April 29, 2022. */
 --QUERY 2
 
-
-
+--counter changing on each new market date
+SELECT
+    customer_id,
+    market_date,
+    ROW_NUMBER() OVER (
+        PARTITION BY customer_id
+        ORDER BY market_date
+    ) AS visit_number
+FROM customer_purchases
+WHERE market_date < '2022-04-29'
+ORDER BY customer_id, market_date;
+
+--select only the unique market dates per customer 
+SELECT
+    customer_id,
+    market_date,
+    DENSE_RANK() OVER (
+        PARTITION BY customer_id
+        ORDER BY market_date
+    ) AS visit_number
+FROM (
+    SELECT DISTINCT customer_id, market_date
+    FROM customer_purchases
+    WHERE market_date < '2022-04-29'
+)
+ORDER BY customer_id, market_date;
 
 --END QUERY
 
@@ -53,8 +78,18 @@ only the customer’s most recent visit.
 HINT: Do not use the previous visit dates filter. */
 --QUERY 3
 
-
-
+SELECT *
+FROM (
+    SELECT
+        customer_id,
+        market_date,
+        ROW_NUMBER() OVER (
+            PARTITION BY customer_id
+            ORDER BY market_date DESC
+        ) AS visit_number_desc
+    FROM customer_purchases
+)
+WHERE visit_number_desc = 1;
 
 --END QUERY
 
@@ -66,8 +101,29 @@ You can make this a running count by including an ORDER BY within the PARTITION
 Filter the visits to dates before April 29, 2022. */
 --QUERY 4
 
-
-
+SELECT
+    customer_id,
+    product_id,
+    market_date,
+    COUNT(*) OVER (
+        PARTITION BY customer_id, product_id
+    ) AS total_purchases_of_product
+FROM customer_purchases
+WHERE market_date < '2022-04-29'
+ORDER BY customer_id, product_id, market_date;
+
+--running count
+SELECT
+    customer_id,
+    product_id,
+    market_date,
+    COUNT(*) OVER (
+        PARTITION BY customer_id, product_id
+        ORDER BY market_date
+    ) AS running_purchase_count
+FROM customer_purchases
+WHERE market_date < '2022-04-29'
+ORDER BY customer_id, product_id, market_date;
 
 --END QUERY
 
@@ -85,21 +141,28 @@ 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. */
 --QUERY 5
 
-
-
+SELECT
+    product_name,
+    CASE 
+        WHEN INSTR(product_name, '-') = 0 THEN NULL
+        ELSE TRIM(
+                SUBSTR(
+                    product_name,
+                    INSTR(product_name, '-') + 1
+                )
+             )
+    END AS description
+FROM product;
 
 --END QUERY
 
-
 /* 2. Filter the query to show any product_size value that contain a number with REGEXP. */
 --QUERY 6
 
-
-
+SELECT * FROM product WHERE product_size REGEXP '[0-9]';
 
 --END QUERY
 
-
 -- UNION
 /* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
 
@@ -111,8 +174,30 @@ HINT: There are a possibly a few ways to do this query, but if you're struggling
 with a UNION binding them. */
 --QUERY 7
 
-
-
+WITH date_totals AS (
+    SELECT
+        market_date,
+        SUM(quantity * cost_to_customer_per_qty) AS total_sales
+    FROM customer_purchases
+    GROUP BY market_date
+),
+ranked_dates AS (
+    SELECT
+        market_date,
+        total_sales,
+        RANK() OVER (ORDER BY total_sales DESC) AS best_rank,
+        RANK() OVER (ORDER BY total_sales ASC)  AS worst_rank
+    FROM date_totals
+)
+SELECT market_date, total_sales, 'Highest Sales Day' AS category
+FROM ranked_dates
+WHERE best_rank = 1
+
+UNION
+
+SELECT market_date, total_sales, 'Lowest Sales Day' AS category
+FROM ranked_dates
+WHERE worst_rank = 1;
 
 --END QUERY
 
@@ -132,8 +217,35 @@ How many customers are there (y).
 Before your final group by you should have the product of those two queries (x*y).  */
 --QUERY 8
 
-
-
+WITH vendor_products AS (
+    SELECT
+        v.vendor_name,
+        p.product_name,
+        vi.original_price
+    FROM (SELECT vendor_id, product_id, original_price FROM vendor_inventory GROUP BY vendor_id, product_id, original_price) vi
+    JOIN vendor v ON vi.vendor_id = v.vendor_id
+    JOIN product p ON vi.product_id = p.product_id
+),
+all_customers AS (
+    SELECT customer_id
+    FROM customer
+),
+vendor_cust AS (
+    SELECT
+        vp.vendor_name,
+        vp.product_name,
+        vp.original_price,
+        cust.customer_id
+    FROM vendor_products vp
+    CROSS JOIN all_customers cust
+)
+SELECT
+    vendor_name,
+    product_name,
+    SUM(original_price * 5) AS total_revenue
+FROM vendor_cust
+GROUP BY vendor_name, product_name
+ORDER BY vendor_name, product_name;
 
 --END QUERY
 
@@ -145,8 +257,11 @@ It should use all of the columns from the product table, as well as a new column
 Name the timestamp column `snapshot_timestamp`. */
 --QUERY 9
 
-
-
+DROP TABLE IF EXISTS product_units;
+CREATE TEMP TABLE product_units AS
+SELECT *,CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
 
 --END QUERY
 
@@ -155,8 +270,22 @@ Name the timestamp column `snapshot_timestamp`. */
 This can be any product you desire (e.g. add another record for Apple Pie). */
 --QUERY 10
 
-
-
+INSERT INTO product_units (
+    product_id,
+    product_name,
+    product_size,
+	product_category_id,
+    product_qty_type,
+    snapshot_timestamp
+)
+VALUES (
+    777,                     
+    'Apple Pie',             
+    'large',
+	6,
+    'unit',                                  
+    CURRENT_TIMESTAMP        
+);
 
 --END QUERY
 
@@ -168,11 +297,16 @@ HINT: If you don't specify a WHERE clause, you are going to have a bad time.*/
 --QUERY 11
 
 
-
+DELETE FROM product_units
+WHERE product_name = 'Apple Pie'
+AND snapshot_timestamp = (
+    SELECT MIN(snapshot_timestamp)
+    FROM product_units
+    WHERE product_name = 'Apple Pie'
+);
 
 --END QUERY
 
-
 -- UPDATE
 /* 1.We want to add the current_quantity to the product_units table. 
 First, add a new column, current_quantity to the table using the following syntax.
@@ -191,10 +325,23 @@ Finally, make sure you have a WHERE statement to update the right row,
 When you have all of these components, you can run the update statement. */
 --QUERY 12
 
+ALTER TABLE product_units
+ADD current_quantity INT;
 
-
+UPDATE product_units
+SET current_quantity =
+    CASE
+        WHEN product_id IN (SELECT product_id FROM vendor_inventory)
+        THEN (
+            SELECT COALESCE(vi.quantity, 0)
+            FROM vendor_inventory vi
+            WHERE vi.product_id = product_units.product_id
+            ORDER BY vi.market_date DESC
+            LIMIT 1
+        )
+        ELSE 0
+    END;
 
 --END QUERY
 
 
-