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Assignment two #2

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Section 1 done
saeedami Jan 31, 2025
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section 2 finished
saeedami Jan 31, 2025
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2 changes: 1 addition & 1 deletion 02_activities/assignments/Assignment2.md
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Expand Up @@ -54,7 +54,7 @@ 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...
Type 1 does not keep a history of addresses, and Type 2 keeps a hitory of customer addresses.
```

***
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214 changes: 85 additions & 129 deletions 02_activities/assignments/assignment2.sql
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@@ -1,133 +1,89 @@
/* ASSIGNMENT 2 */
/* SECTION 2 */

-- COALESCE
/* 1. Our favourite manager wants a detailed long list of products, but is afraid of tables!
We tell them, no problem! We can produce a list with all of the appropriate details.

Using the following syntax you create our super cool and not at all needy manager a list:

--section 2
--COALESCE
---Q1
SELECT
product_name || ', ' || product_size|| ' (' || product_qty_type || ')'
FROM product

But wait! The product table has some bad data (a few NULL values).
Find the NULLs and then using COALESCE, replace the NULL with a
blank for the first problem, and 'unit' for the second problem.

HINT: keep the syntax the same, but edited the correct components with the string.
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.) */


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
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(). */



/* 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. */



/* 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. */



-- String manipulations
/* 1. Some product names in the product table have descriptions like "Jar" or "Organic".
These are separated from the product name with a hyphen.
Create a column using SUBSTR (and a couple of other commands) that captures these, but is otherwise NULL.
Remove any trailing or leading whitespaces. Don't just use a case statement for each product!

| product_name | description |
|----------------------------|-------------|
| Habanero Peppers - Organic | Organic |

Hint: you might need to use INSTR(product_name,'-') to find the hyphens. INSTR will help split the column. */



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



-- UNION
/* 1. Using a UNION, write a query that displays the market dates with the highest and lowest total sales.

HINT: There are a possibly a few ways to do this query, but if you're struggling, try the following:
1) Create a CTE/Temp Table to find sales values grouped dates;
2) Create another CTE/Temp table with a rank windowed function on the previous query to create
"best day" and "worst day";
3) Query the second temp table twice, once for the best day, once for the worst day,
with a UNION binding them. */




/* SECTION 3 */

-- Cross Join
/*1. Suppose every vendor in the `vendor_inventory` table had 5 of each of their products to sell to **every**
customer on record. How much money would each vendor make per product?
Show this by vendor_name and product name, rather than using the IDs.

HINT: Be sure you select only relevant columns and rows.
Remember, CROSS JOIN will explode your table rows, so CROSS JOIN should likely be a subquery.
Think a bit about the row counts: how many distinct vendors, product names are there (x)?
How many customers are there (y).
Before your final group by you should have the product of those two queries (x*y). */



-- 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`. */



/*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). */



-- 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.*/



-- 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.

---Q1

SELECT customer_id,(row_number() OVER ( PARTITION by customer_id order by market_date) )as customer_visits, market_date FROM customer_purchases;

----Q2
WITH new_table as(
SELECT
customer_id,(row_number() OVER ( PARTITION by customer_id ORDER by market_date DESC) )as customer_visits,
market_date FROM customer_purchases)
SELECT customer_id, market_date as last_visit from new_table where customer_visits=1 ;

----Q3

SELECT *,(count() OVER ( PARTITION by product_id ,customer_id) )as product_purchase_count FROM customer_purchases;

--String manipulations
---Q1

SELECT product_name,

CASE
WHEN instr(product_name,'-') !=0 THEN
replace(substr(product_name,instr(product_name,'-')+1,length(product_name)),' ','')
ELSE
NULL
END
as description FROM product;

--UNION
---Q1

with date_sales as (SELECT market_date, sum(quantity*cost_to_customer_per_qty) as sales from customer_purchases GROUP by market_date)

select max(sales) as 'min/max', market_date from date_sales
UNION
select min(sales)as 'min/max', market_date from date_sales;

--section3
--Cross Join
---Q1
WITH customers_total AS (
SELECT COUNT(*) AS customer_count FROM customer
),
vendor_product_prices AS (
SELECT
product_id,
vendor_name,
original_price AS price
FROM vendor_inventory
JOIN vendor ON vendor_inventory.vendor_id = vendor.vendor_id
),
result AS (
SELECT
DISTINCT vendor_product_prices.vendor_name, vendor_product_prices.price * 5 * customers_total.customer_count AS total_revenue
FROM vendor_product_prices
CROSS JOIN customers_total
ORDER BY vendor_product_prices.vendor_name, vendor_product_prices.product_id
)
SELECT vendor_name,sum(total_revenue) from result GROUP by vendor_name;
--INSERT
---Q1
CREATE TABLE IF NOT EXISTS product_units AS
SELECT *, snapshot_timestamp
FROM product
WHERE product_qty_type = 'unit';
---Q2
INSERT INTO product_units (product_id, product_name, product_size, product_category_id, product_qty_type, snapshot_timestamp)
VALUES (7, 'Apple Pie', '10"', '3','unit', '2012-05-06 12:48:00');
--DELETE
---Q1
DELETE FROM product_units
WHERE product_name = 'Apple Pie'
AND snapshot_timestamp < (
SELECT MAX(snapshot_timestamp)
FROM product_units
WHERE product_name = 'Apple Pie'
);
--UPDATE
---Q1
ALTER TABLE product_units
ADD current_quantity INT;

Then, using UPDATE, change the current_quantity equal to the last quantity value from the vendor_inventory details.

HINT: This one is pretty hard.
First, determine how to get the "last" quantity per product.
Second, coalesce null values to 0 (if you don't have null values, figure out how to rearrange your query so you do.)
Third, SET current_quantity = (...your select statement...), remembering that WHERE can only accommodate one column.
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 COLUMN current_quantity INT;
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