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0a3f40c
completed assignment 2
ltonello Dec 29, 2024
ac9ba4e
completed assignment 2 with ERDs"
ltonello Dec 29, 2024
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Binary file added 02_activities/assignments/Assignment 2 Prompt 1 ERD.drawio.pdf
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4 changes: 3 additions & 1 deletion 02_activities/assignments/Assignment2.md
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Expand Up @@ -54,7 +54,9 @@ The store wants to keep customer addresses. Propose two architectures for the CU
**HINT:** search type 1 vs type 2 slowly changing dimensions.

```
Your answer...
To retain changes to customer addresses, the bookstore would use a type 2 slowly changing dimension. In this case, each time a customer's address is updated, a new row is created. For this to work, the database will have to assign a new customer ID to the customer each time their address is changed and the customer will be treated as a new customer in the database.

To overwrite changes to customer addresses, you would use a type 1 slowly changing dimension. This will simply overwrite the customer's existing address with the new one.
```

***
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126 changes: 124 additions & 2 deletions 02_activities/assignments/assignment2.sql
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Expand Up @@ -20,6 +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(NULLIF(product_size, ''), ' ') || ' (' || coalesce(NULLIF(product_qty_type, ''), 'unit') || ')'
FROM product;


--Windowed Functions
Expand All @@ -32,17 +35,33 @@ 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 *
,dense_rank() OVER(PARTITION BY customer_id ORDER BY market_date ASC) as number_of_customer_visits

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. */

SELECT *
FROM (
SELECT *
,row_number() OVER(PARTITION BY customer_id ORDER BY market_date DESC) as most_recent_customer_visit

FROM customer_purchases
) as x
WHERE x.most_recent_customer_visit = 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 *
,count() OVER(PARTITION BY customer_id, product_id ORDER BY product_id ASC) as number_of_product_purchases

FROM customer_purchases;


-- String manipulations
Expand All @@ -57,11 +76,23 @@ 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 *
,CASE WHEN product_name like '%-%'
THEN substr (product_name, (instr(product_name, '-'))+2)
END as description

FROM product;


/* 2. Filter the query to show any product_size value that contain a number with REGEXP. */

SELECT *
,CASE WHEN product_name like '%-%'
THEN substr (product_name, (instr(product_name, '-'))+2)
END as description

FROM product
WHERE product_size REGEXP '\d';

-- UNION
/* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.
Expand All @@ -73,7 +104,47 @@ 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)
DROP TABLE IF EXISTS sales_values_grouped;
CREATE TEMP TABLE sales_values_grouped AS

SELECT *
,sum(quantity*cost_to_customer_per_qty) as total_cost_per_day
FROM customer_purchases
GROUP BY market_date;

SELECT * FROM sales_values_grouped;

--2)
DROP TABLE IF EXISTS sales_values_ranked;
CREATE TEMP TABLE sales_values_ranked AS

SELECT *
,row_number() OVER(ORDER BY total_cost_per_day DESC) as sales_values_per_day_ranked
FROM sales_values_grouped;

SELECT * FROM sales_values_ranked;

--3)
SELECT *
FROM (
SELECT *
,row_number() OVER(ORDER BY total_cost_per_day DESC) as best_or_worst
FROM sales_values_ranked
) as x

WHERE x.best_or_worst = 1

UNION

SELECT *
FROM (
SELECT *
,row_number() OVER(ORDER BY total_cost_per_day ASC) as best_or_worst
FROM sales_values_ranked
) as x

WHERE x.best_or_worst = 1;


/* SECTION 3 */
Expand All @@ -89,6 +160,24 @@ 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). */

DROP TABLE IF EXISTS vendor_products;
CREATE TEMP TABLE vendor_products as

SELECT DISTINCT v.vendor_name
,p.product_name
,vi.original_price*5 as total_price_qty_5
FROM vendor_inventory as vi
INNER JOIN vendor as v
on vi.vendor_id = v.vendor_id
INNER JOIN product as p
on vi.product_id = p.product_id;

SELECT * FROM vendor_products;

SELECT vendor_name, product_name, customer_id, sum(total_price_qty_5) as total_price_qty_5_all_customers
FROM vendor_products
CROSS JOIN customer
GROUP BY product_name;


-- INSERT
Expand All @@ -97,18 +186,30 @@ 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 TEMP TABLE product_units as

SELECT *
, CURRENT_TIMESTAMP as snapshot_timestamp
FROM product
WHERE product_qty_type = 'unit'
ORDER BY product_id;


/*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
VALUES (24, 'Peach Pie', '10"', 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 = 24;


-- UPDATE
Expand All @@ -128,6 +229,27 @@ 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
SET current_quantity =
ifnull((
SELECT
quantity
FROM (
SELECT *
FROM (
SELECT vi.product_id
,p.product_name
,vi.market_date
,vi.quantity
,row_number() OVER(PARTITION BY vi.product_id ORDER BY market_date DESC) as last_quantity_per_product
FROM vendor_inventory as vi
LEFT JOIN product as p
on vi.product_id = p.product_id
) as x
WHERE x.last_quantity_per_product = 1) as y
WHERE product_units.product_id = y.product_id), 0);

SELECT * FROM product_units