Assignment 2 Natalia Rodriguez

02_activities/assignments/assignment2.sql

@@ -20,7 +20,11 @@ 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 
+  COALESCE(product_name, '') || ', ' || 
+  COALESCE(product_size, '') || ' (' || 
+  COALESCE(product_qty_type, 'unit') || ')' AS product_description
+FROM product;
 
 --Windowed Functions
 /* 1. Write a query that selects from the customer_purchases table and numbers each customer’s  
@@ -32,18 +36,47 @@ 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,
+  DENSE_RANK() OVER (
+    PARTITION BY customer_id 
+    ORDER BY market_date
+  ) AS visit_number
+FROM (
+  SELECT DISTINCT customer_id, market_date
+  FROM customer_purchases
+) AS 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. */
 
-
+SELECT *
+FROM (
+  SELECT 
+    customer_id,
+    market_date,
+    DENSE_RANK() OVER (
+      PARTITION BY customer_id 
+      ORDER BY market_date DESC
+    ) AS visit_number
+  FROM (
+    SELECT DISTINCT customer_id, market_date
+    FROM customer_purchases
+  ) AS visits
+) AS ranked_visits
+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,
+count(*) OVER(PARTITION BY customer_id, product_id
+  ) AS customer_product_count
+FROM customer_purchases
 
 -- String manipulations
 /* 1. Some product names in the product table have descriptions like "Jar" or "Organic". 
@@ -57,11 +90,21 @@ 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
 
 /* 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
 /* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
@@ -73,7 +116,36 @@ 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. */
 
+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 best_day_rank,
+    RANK() OVER (ORDER BY total_sales ASC) AS worst_day_rank
+  FROM daily_sales
+)
+SELECT 
+  market_date,
+  total_sales,
+  'Best Day' AS label
+FROM ranked_sales
+WHERE best_day_rank = 1
 
+UNION
+
+SELECT 
+  market_date,
+  total_sales,
+  'Worst Day' AS label
+FROM ranked_sales
+WHERE worst_day_rank = 1;
 
 
 /* SECTION 3 */
@@ -89,6 +161,35 @@ 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).  */
 
+WITH vendor_products AS (
+  SELECT DISTINCT 
+    v.vendor_id,
+    v.product_id,
+    v.original_price,
+    vendor_name,
+    product_name
+  FROM vendor_inventory v
+  JOIN vendor USING (vendor_id)
+  JOIN product USING (product_id)
+),
+customers AS (
+  SELECT customer_id FROM customer
+),
+sales_5 AS (
+  SELECT 
+    vp.vendor_name,
+    vp.product_name,
+    5 * vp.original_price AS revenue_per_customer
+  FROM vendor_products vp
+  CROSS JOIN customers
+)
+SELECT 
+  vendor_name,
+  product_name,
+  SUM(revenue_per_customer) AS total_revenue
+FROM sales_5
+GROUP BY vendor_name, product_name
+ORDER BY vendor_name, product_name
 
 
 -- INSERT
@@ -102,14 +203,33 @@ Name the timestamp column `snapshot_timestamp`. */
 /*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). */
 
+CREATE TABLE product_units AS
+SELECT 
+  *,
+  CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
+
+SELECT*
+FROM product_units;
 
+INSERT INTO product_units (product_id, product_name, product_size, product_category_id, product_qty_type, snapshot_timestamp)
+VALUES (24, 'Coffee', '500g', 3, 'unit', CURRENT_TIMESTAMP);
+
+SELECT*
+FROM product_units;
 
 -- 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 = 'Coffee'
+  AND snapshot_timestamp = (
+    SELECT MIN(snapshot_timestamp)
+    FROM product_units
+    WHERE product_name = 'Coffee')
 
 -- UPDATE
 /* 1.We want to add the current_quantity to the product_units table. 
@@ -127,7 +247,22 @@ Third, SET current_quantity = (...your select statement...), remembering that WH
 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;
+
+UPDATE product_units pu
+SET current_quantity = (
+  SELECT 
+    COALESCE(vi.quantity, 0)
+  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)
+  LIMIT 1)
 
 
+--Natalia Rodriguez