Assignment 2

02_activities/assignments/Cohort_8/assignment2.sql

@@ -21,7 +21,14 @@ 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. */
 
+DROP VIEW IF EXISTS list_for_products;
+CREATE VIEW IF NOT EXISTS list_for_products AS
 
+SELECT 
+coalesce (product_name, '') || ', ' || coalesce (product_size, '') || ' (' || coalesce (product_qty_type, 'unit') || ')' AS list_of_products
+FROM product;
+
+SELECT * from list_for_products ;
 
 
 --Windowed Functions
@@ -34,18 +41,46 @@ 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,
+    transaction_time,
+    ROW_NUMBER() OVER (PARTITION BY customer_id  ORDER BY market_date, transaction_time) AS No_of_visit
+FROM customer_purchases
+ORDER BY customer_id, market_date, transaction_time;
 
 
 /* 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 
+    customer_id,
+    market_date,
+    transaction_time
+FROM (
+    SELECT 
+        customer_id,
+        market_date,
+        transaction_time,
+        DENSE_RANK() OVER (PARTITION BY customer_id ORDER BY market_date DESC) AS No_of_visit
+    FROM customer_purchases
+) AS ranked_visits
+WHERE No_of_visit= 1
+ORDER BY customer_id;
 
 
 /* 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,
+    transaction_time,
+    COUNT(*) OVER (PARTITION BY customer_id, product_id) AS times_purchased_this_product
+FROM customer_purchases
+ORDER BY customer_id, product_id, market_date;
 
 -- String manipulations
 /* 1. Some product names in the product table have descriptions like "Jar" or "Organic". 
@@ -59,10 +94,32 @@ 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 value_of_product
+FROM product;
 
 
 /* 2. Filter the query to show any product_size value that contain a number with REGEXP. */
 
+SELECT 
+    product_id,
+    product_name,
+    product_size,
+    CASE 
+        WHEN INSTR(product_name, '-') > 0 THEN 
+            TRIM(SUBSTR(product_name, INSTR(product_name, '-') + 1))
+        ELSE 
+            NULL
+    END AS value_of_product
+FROM product
+WHERE product_size REGEXP '[0-9]'
+ORDER BY product_name;
 
 
 -- UNION
@@ -75,6 +132,43 @@ 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. */
 
+-- Step 1:
+WITH daily_sales AS (
+    SELECT 
+        market_date,
+        SUM(quantity * cost_to_customer_per_qty) AS total_sales
+    FROM customer_purchases
+    GROUP BY market_date
+),
+
+-- Step 2:
+ranked_sales AS (
+    SELECT 
+        market_date,
+        total_sales,
+        RANK() OVER (ORDER BY total_sales DESC) AS rank_best,
+        RANK() OVER (ORDER BY total_sales ASC) AS rank_worst
+    FROM daily_sales
+)
+
+-- Step 3: 
+SELECT 
+    market_date,
+    total_sales,
+    'Highest Sales' AS sales_type
+FROM ranked_sales
+WHERE rank_best = 1
+
+UNION
+
+SELECT 
+    market_date,
+    total_sales,
+    'Lowest Sales' AS sales_type
+FROM ranked_sales
+WHERE rank_worst = 1
+
+ORDER BY total_sales DESC;
 
 
 
@@ -92,19 +186,82 @@ 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,
+    COUNT(DISTINCT c.customer_id) AS number_of_customers,
+    COUNT(DISTINCT c.customer_id) * 5 AS total_units_sold,
+    COUNT(DISTINCT c.customer_id) * 5 * vi.original_price AS total_revenue_per_product
+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
+CROSS JOIN customer c
+GROUP BY v.vendor_id, v.vendor_name, p.product_id, p.product_name, vi.original_price
+ORDER BY 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`. */
 
+DROP TABLE IF EXISTS product_units;
+CREATE TABLE product_units (
+    product_id INT(11) NOT NULL,
+    product_name VARCHAR(45) DEFAULT NULL,
+    product_size VARCHAR(45) DEFAULT NULL,
+    product_category_id INT(11) NOT NULL,
+    product_qty_type VARCHAR(45) DEFAULT NULL,
+    snapshot_timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (product_id, snapshot_timestamp)
+);
+
+INSERT INTO product_units (
+    product_id,
+    product_name,
+    product_size,
+    product_category_id,
+    product_qty_type,
+    snapshot_timestamp
+)
+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';
 
+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 (
+    999,                    -- product_id (use a unique ID)
+    'Apple Pie',           -- product_name
+    'Large',               -- product_size
+    1,                     -- product_category_id (adjust to valid category)
+    'unit',                -- product_qty_type
+    CURRENT_TIMESTAMP      -- snapshot_timestamp (current time)
+);
+SELECT * FROM product_units;
 
 -- DELETE
 /* 1. Delete the older record for the whatever product you added. 
@@ -113,6 +270,7 @@ HINT: If you don't specify a WHERE clause, you are going to have a bad time.*/
 
 
 
+
 -- 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.
@@ -130,6 +288,24 @@ 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 current_quantity INT;
 
 
-
+-- Step 2: Update with last quantity per product
+UPDATE product_units
+SET current_quantity = (
+    SELECT COALESCE(SUM(vi.quantity), 0)
+    FROM vendor_inventory vi
+    WHERE vi.product_id = product_units.product_id
+      AND vi.market_date = (
+          SELECT MAX(vi2.market_date)
+          FROM vendor_inventory vi2
+          WHERE vi2.product_id = product_units.product_id
+      )
+)
+WHERE product_units.product_id IN (
+    SELECT DISTINCT product_id 
+    FROM vendor_inventory
+);
+SELECT * FROM product_units;