Assignment two

02_activities/assignments/Assignment2.md

@@ -56,8 +56,35 @@ The store wants to keep customer addresses. Propose two architectures for the CU
 ```
 Your answer...
 ```
-
-***
+Type 1 (Overwriting)
+CUSTOMER_ADDRESS (Type 1)
+- address_id (PK)
+- customer_id (FK)
+- apartment
+- street
+- city
+- state
+- postal_code
+- country
+- is_primary
+This architecture only maintains customer's current address, every time it updates it overwrites previous address.
+
+Type 2 (Historical Retention)
+CUSTOMER_ADDRESS (Type 2)
+- address_id (PK)
+- customer_id (FK)
+- apartment
+- street
+- city
+- state
+- postal_code
+- country
+- is_primary
+- effective_date
+- end_date
+- current_flag (Y/N)
+
+The 2nd architecture keeps historical address for the customer through including the effective date and end date also with a indicator to identify the current active address. Every time it updates it will append the new records. 
 
 ## Section 2:
 You can start this section following *session 4*.

02_activities/assignments/assignment2.sql

@@ -20,7 +20,9 @@ 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, 'unit') || ')'
+FROM product;
 
 --Windowed Functions
 /* 1. Write a query that selects from the customer_purchases table and numbers each customer’s  
@@ -32,18 +34,85 @@ 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(). */
 
+-- Approache One uses ROW_NUMBER()
+SELECT 
+    m.*,
+    ROW_NUMBER() OVER (
+        PARTITION BY customer_id 
+        ORDER BY market_date
+    ) AS customer_visit_number
+FROM 
+    customer_purchases m;
 
+-- Approache One uses DENSE_RANK()
+
+SELECT 
+    customer_id,
+    market_date,
+    DENSE_RANK() OVER (
+        PARTITION BY customer_id 
+        ORDER BY market_date
+    ) AS customer_visit_number
+FROM 
+    (SELECT DISTINCT customer_id, market_date FROM customer_purchases) AS unique_visits;
 
 /* 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. */
 
+-- Approache One uses ROW_NUMBER() reverser
+SELECT 
+    m.*,
+    ROW_NUMBER() OVER (
+        PARTITION BY customer_id 
+        ORDER BY market_date DESC
+    ) AS customer_visit_number
+FROM 
+    customer_purchases m;
 
+-- Approache One uses DENSE_RANK() reverser
+
+SELECT 
+    customer_id,
+    market_date,
+    DENSE_RANK() OVER (
+        PARTITION BY customer_id 
+        ORDER BY market_date DESC
+    ) AS customer_visit_number
+FROM 
+    (SELECT DISTINCT customer_id, market_date FROM customer_purchases) AS unique_visits;
+
+-- 
+
+WITH ranked_visits AS (
+    SELECT 
+        customer_id,
+        market_date,
+        ROW_NUMBER() OVER (
+            PARTITION BY customer_id 
+            ORDER BY market_date DESC
+        ) AS visit_rank
+    FROM 
+        (SELECT DISTINCT customer_id, market_date FROM customer_purchases) AS unique_visits
+)
+SELECT 
+    customer_id,
+    market_date AS most_recent_visit_date
+FROM 
+    ranked_visits
+WHERE 
+    visit_rank = 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 
+    cp.*,
+    COUNT(*) OVER (
+        PARTITION BY customer_id, product_id
+    ) AS customer_product_purchase_count
+FROM 
+    customer_purchases cp;
 
 -- String manipulations
 /* 1. Some product names in the product table have descriptions like "Jar" or "Organic". 
@@ -57,7 +126,18 @@ 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,
+    CASE 
+        WHEN INSTR(product_name, '-') > 0 
+        THEN TRIM(SUBSTR(
+            product_name, 
+            INSTR(product_name, '-') + 1
+        ))
+        ELSE NULL 
+    END AS description
+FROM 
+    product;
 
 
 -- UNION
@@ -71,7 +151,41 @@ HINT: There are a possibly a few ways to do this query, but if you're struggling
 with a UNION binding them. */
 
 
-
+WITH daily_sales AS (
+    SELECT 
+        market_date,
+        SUM(quantity * cost_to_customer_per_qty) AS total_sales
+    FROM 
+        customer_purchases
+    GROUP BY 
+        market_date
+)
+
+SELECT * FROM (
+    SELECT 
+        market_date,
+        total_sales,
+        'Highest Sales Day' AS sales_category
+    FROM 
+        daily_sales
+    ORDER BY 
+        total_sales DESC
+    LIMIT 1
+) AS highest
+
+UNION ALL
+
+SELECT * FROM (
+    SELECT 
+        market_date,
+        total_sales,
+        'Lowest Sales Day' AS sales_category
+    FROM 
+        daily_sales
+    ORDER BY 
+        total_sales ASC
+    LIMIT 1
+) AS lowest;
 
 /* SECTION 3 */
 
@@ -87,26 +201,70 @@ 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,
+    (5 * vi.original_price * (SELECT COUNT(*) FROM customer)) AS projected_revenue
+FROM (
+    SELECT DISTINCT vendor_id, product_id, original_price
+    FROM vendor_inventory
+) vi
+JOIN vendor v ON vi.vendor_id = v.vendor_id
+JOIN product p ON vi.product_id = p.product_id
+ORDER BY projected_revenue DESC, v.vendor_name, p.product_name;
+
 
 -- INSERT
 /*1.  Create a new table "product_units". 
 This table will contain only products where the `product_qty_type = 'unit'`. 
 It should use all of the columns from the product table, as well as a new column for the `CURRENT_TIMESTAMP`.  
 Name the timestamp column `snapshot_timestamp`. */
 
-
+CREATE TABLE product_units AS
+SELECT 
+    p.*,
+    CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM 
+    product p
+WHERE 
+    product_qty_type = 'unit';
 
 /*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 (
+    (SELECT MAX(product_id) + 1 FROM product_units), -- Auto-generate a new ID
+    'Butter Tart',
+    '1 dozen',
+   3,
+    'unit',
+    CURRENT_TIMESTAMP
+);
 
 
 -- 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_id = (
+    SELECT product_id 
+    FROM product_units
+    WHERE product_name = 'Butter Tart'
+    ORDER BY snapshot_timestamp ASC
+    LIMIT 1
+)
+AND product_name = 'Butter Tart';
 
 -- UPDATE
 /* 1.We want to add the current_quantity to the product_units table. 
@@ -126,5 +284,17 @@ 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. */
 
 
-
-
+UPDATE product_units pu
+SET current_quantity = COALESCE(
+    (
+        SELECT vi.quantity
+        FROM vendor_inventory vi
+        WHERE vi.product_id = pu.product_id
+        AND vi.market_date = (
+            SELECT MAX(market_date)
+            FROM vendor_inventory
+            WHERE product_id = pu.product_id
+        )
+    ), 
+    0
+);