Assignment two

02_activities/assignments/assignment2.sql

@@ -20,29 +20,116 @@ 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') || ')' AS product_details
+FROM product;
 
 
 --Windowed Functions
 /* 1. Write a query that selects from the customer_purchases table and numbers each customer’s  
 visits to the farmer’s market (labeling each market date with a different number). 
 Each customer’s first visit is labeled 1, second visit is labeled 2, etc. 
 
+
 You can either display all rows in the customer_purchases table, with the counter changing on
 each new market date for each customer, or select only the unique market dates per customer 
 (without purchase details) and number those visits. 
 HINT: One of these approaches uses ROW_NUMBER() and one uses DENSE_RANK(). */
 
+ --use ROW_NUMBER() 
+ SELECT 
+	customer_id,
+	market_date,
+ROW_NUMBER() OVER (
+	PARTITION BY customer_id
+	ORDER BY market_date
+) AS visit_number
+FROM customer_purchases;
+
+ --use DENSE_RANK (it wont skip any number)
+SELECT 
+  customer_id,
+  market_date,
+  DENSE_RANK() 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. */
 
+--reverse using dense_rank
+SELECT 
+  customer_id,
+  market_date,
+  DENSE_RANK() OVER (
+    PARTITION BY customer_id
+    ORDER BY market_date DESC
+  ) AS reverse_visit_number
+FROM customer_purchases;
+
+--reverse using row_number
+SELECT 
+  customer_id,
+  market_date,
+  ROW_NUMBER() OVER (
+    PARTITION BY customer_id
+    ORDER BY market_date DESC
+  ) AS reverse_visit_number
+FROM customer_purchases;
+
+-- most recent visit using dense_rank
+SELECT 
+  customer_id,
+  market_date
+FROM (
+  SELECT
+    customer_id,
+    market_date,
+    DENSE_RANK() OVER (
+      PARTITION BY customer_id
+      ORDER BY market_date DESC
+    ) AS reverse_visit_number
+  FROM customer_purchases
+) AS customer_most_rencent_visit
+WHERE reverse_visit_number = 1;
+
+--most recent using row_number
+SELECT
+  customer_id,
+  market_date
+FROM (
+  SELECT 
+    customer_id,
+    market_date,
+    ROW_NUMBER() OVER (
+      PARTITION BY customer_id
+      ORDER BY market_date DESC
+    ) AS reverse_visit_number
+  FROM customer_purchases
+) AS customer_most_recent_visit
+WHERE reverse_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,
+  quantity,
+  market_date,
+  COUNT(*) OVER (
+    PARTITION BY customer_id, product_id
+  ) AS times_purchased
+FROM customer_purchases;
 
 
 -- String manipulations
@@ -57,10 +144,24 @@ 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,
+  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 
+  product_name,
+  product_size
+FROM product
+WHERE product_size REGEXP '[0-9]';
 
 
 -- UNION
@@ -73,7 +174,47 @@ 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. */
 
+-- 1. create temp sales table 
+DROP TABLE IF EXISTS temp_sales_by_date;
+CREATE TEMP TABLE temp_sales_by_date AS
+SELECT 
+  market_date,
+  SUM(quantity * original_price) AS total_sales
+FROM vendor_inventory
+GROUP BY market_date;
+
+--check 
+select * from temp_sales_by_date;
 
+--2. Second temp table for best and worse day
+DROP TABLE IF EXISTS temp_ranked_sales;
+CREATE TEMP TABLE temp_ranked_sales AS
+SELECT 
+  market_date,
+  total_sales,
+  RANK() OVER (ORDER BY total_sales DESC) AS best_day,
+  RANK() OVER (ORDER BY total_sales ASC) AS worst_day
+FROM temp_sales_by_date;
+
+--check 
+SELECT * FROM temp_ranked_sales;
+
+--3 use union
+SELECT 
+  market_date,
+  total_sales,
+  'Best Day' AS day_type
+FROM temp_ranked_sales
+WHERE best_day = 1
+
+UNION
+
+SELECT 
+  market_date,
+  total_sales,
+  'Worst Day' AS day_type
+FROM temp_ranked_sales
+WHERE worst_day= 1;
 
 
 /* SECTION 3 */
@@ -89,6 +230,18 @@ 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 total_revenue
+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_name,
+  p.product_name;
 
 
 -- INSERT
@@ -97,18 +250,45 @@ 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 AS
+SELECT 
+  *,
+  CURRENT_TIMESTAMP AS snapshot_timestamp
+FROM product
+WHERE product_qty_type = 'unit';
+
+INSERT INTO product_units (product_id, product_name, product_size, product_qty_type, snapshot_timestamp)
+SELECT 
+  product_id, 
+  product_name, 
+  product_size, 
+  product_qty_type, 
+  CURRENT_TIMESTAMP
+FROM product
+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_qty_type,
+  snapshot_timestamp
+)
+VALUES (88, 'Chocolate Fudge Cake', '10"', '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_name = 'Chocolate Fudge Cake';
 
 
 -- UPDATE
@@ -128,6 +308,19 @@ 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. */
 
+--add new column
+ALTER TABLE product_units
+ADD COLUMN current_quantity INT;
+
+UPDATE product_units
+SET current_quantity = COALESCE((
+  SELECT vi.quantity
+  FROM vendor_inventory vi
+  WHERE vi.product_id = product_units.product_id
+), 0);
+
+select * from product_units;
+