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Committing Homework #1

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22cbe41
Commiting homework_1 and homework_2
gzuo May 16, 2024
c1c8111
Committing homework_3
gzuo May 18, 2024
b230978
Merge branch 'main' of https://github.com/gzuo/sql into homework
gzuo May 23, 2024
f83094a
Commit homework_4
gzuo May 24, 2024
37f3444
Commit homework_5.sql
gzuo May 24, 2024
3215377
Commit homework_6.md
gzuo May 24, 2024
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38 changes: 33 additions & 5 deletions 03_homework/homework_2.sql
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@@ -1,42 +1,70 @@
--SELECT
/* 1. Write a query that returns everything in the customer table. */

SELECT * FROM customer


/* 2. Write a query that displays all of the columns and 10 rows from the cus- tomer table,
sorted by customer_last_name, then customer_first_ name. */

SELECT * FROM customer
ORDER BY customer_last_name, customer_first_name
LIMIT 10



--WHERE
/* 1. Write a query that returns all customer purchases of product IDs 4 and 9. */
-- option 1
SELECT * FROM customer_purchases
WHERE product_id IN (4, 9)

-- option 2
SELECT * FROM customer_purchases
WHERE product_id = 4 or product_id = 9


/*2. Write a query that returns all customer purchases and a new calculated column 'price' (quantity * cost_to_customer_per_qty),
filtered by vendor IDs between 8 and 10 (inclusive) using either:
1. two conditions using AND
2. one condition using BETWEEN
*/
-- option 1

SELECT *, (quantity * cost_to_customer_per_qty) AS price
FROM customer_purchases
WHERE vendor_id >= 8 AND vendor_id <= 10

-- option 2
SELECT *, (quantity * cost_to_customer_per_qty) AS price
FROM customer_purchases
WHERE vendor_id BETWEEN 8 AND 10


--CASE
/* 1. Products can be sold by the individual unit or by bulk measures like lbs. or oz.
Using the product table, write a query that outputs the product_id and product_name
columns and add a column called prod_qty_type_condensed that displays the word “unit”
if the product_qty_type is “unit,” and otherwise displays the word “bulk.” */

SELECT product_id, product_name,
CASE WHEN product_qty_type = 'unit' THEN 'unit'
ELSE 'bulk'
END AS prod_qty_type_condensed
FROM product

/* 2. We want to flag all of the different types of pepper products that are sold at the market.
add a column to the previous query called pepper_flag that outputs a 1 if the product_name
contains the word “pepper” (regardless of capitalization), and otherwise outputs 0. */

SELECT product_id, product_name,
CASE WHEN product_qty_type = 'unit' THEN 'unit'
ELSE 'bulk'
END AS prod_qty_type_condensed,
CASE WHEN lower(product_name) like '%pepper%' THEN 1
ELSE 0
END AS pepper_flag
FROM product

--JOIN
/* 1. Write a query that INNER JOINs the vendor table to the vendor_booth_assignments table on the
vendor_id field they both have in common, and sorts the result by vendor_name, then market_date. */
SELECT *
FROM vendor v INNER JOIN vendor_booth_assignments vba
ON v.vendor_id = vba.vendor_id
ORDER BY v.vendor_name, vba.market_date
27 changes: 27 additions & 0 deletions 03_homework/homework_3.sql
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Expand Up @@ -2,6 +2,9 @@
/* 1. Write a query that determines how many times each vendor has rented a booth
at the farmer’s market by counting the vendor booth assignments per vendor_id. */

SELECT vendor_id, COUNT(*) as rent_count
FROM vendor_booth_assignments
GROUP by vendor_id


/* 2. The Farmer’s Market Customer Appreciation Committee wants to give a bumper
Expand All @@ -10,6 +13,11 @@ of customers for them to give stickers to, sorted by last name, then first name.

HINT: This query requires you to join two tables, use an aggregate function, and use the HAVING keyword. */

SELECT c.*, sum(quantity * cost_to_customer_per_qty) as spent
FROM customer c INNER JOIN customer_purchases cp ON c.customer_id = cp.customer_id
GROUP by cp.customer_id
HAVING sum(cp.quantity * cp.cost_to_customer_per_qty) > 2000
ORDER by c.customer_first_name, c.customer_last_name


--Temp Table
Expand All @@ -24,17 +32,36 @@ When inserting the new vendor, you need to appropriately align the columns to be
VALUES(col1,col2,col3,col4,col5)
*/

CREATE TEMPORARY TABLE temp.new_vendor AS SELECT * FROM vendor

INSERT INTO temp.new_vendor (vendor_id, vendor_name, vendor_type, vendor_owner_first_name, vendor_owner_last_name)
VALUES (10, 'Thomass Superfood Store', 'Fresh Focused', 'Thomas', 'Rosenthal')

SELECT * FROM temp.new_vendor

-- Date
/*1. Get the customer_id, month, and year (in separate columns) of every purchase in the customer_purchases table.

HINT: you might need to search for strfrtime modifers sqlite on the web to know what the modifers for month
and year are! */

SELECT customer_id,
strftime('%m', market_date) AS month,
strftime('%Y', market_date) AS year
FROM customer_purchases


/* 2. Using the previous query as a base, determine how much money each customer spent in April 2019.
Remember that money spent is quantity*cost_to_customer_per_qty.

HINTS: you will need to AGGREGATE, GROUP BY, and filter...
but remember, STRFTIME returns a STRING for your WHERE statement!! */

SELECT customer_id,
quantity * cost_to_customer_per_qty as spent
FROM customer_purchases
WHERE strftime('%Y%m', market_date) = '201904'
GROUP by customer_id



70 changes: 67 additions & 3 deletions 03_homework/homework_4.sql
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Expand Up @@ -17,7 +17,9 @@ 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(product_size, '') || ' (' || COALESCE(product_qty_type, 'unit') || ')' AS Product_Detail
FROM product


--Windowed Functions
Expand All @@ -30,17 +32,49 @@ 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,
ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date) AS visit
FROM
(SELECT DISTINCT customer_id, market_date FROM customer_purchases) cp


/* 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,
ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY market_date) AS visit
FROM
(SELECT DISTINCT customer_id, market_date FROM customer_purchases) cp
) v
WHERE v.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 DISTINCT
customer_id,
product_id,
count(*) OVER (PARTITION BY customer_id, product_id) AS purchases_times
FROM
customer_purchases cp


--Or, I prefer the following but the count function is not used as window function
SELECT
customer_id,
product_id,
count(*) AS purchases_times
FROM
customer_purchases cp
GROUP by
customer_id,
product_id


-- String manipulations
/* 1. Some product names in the product table have descriptions like "Jar" or "Organic".
Expand All @@ -54,10 +88,20 @@ 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,
nullif(trim(substr(product_name, INSTR(product_name,'-') + 1)), product_name) 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
Expand All @@ -71,5 +115,25 @@ HINT: There are a possibly a few ways to do this query, but if you're struggling
with a UNION binding them. */



WITH daily_sales AS (
SELECT
market_date,
SUM(quantity * cost_to_customer_per_qty) AS daily_sales
FROM
customer_purchases
GROUP BY
market_date
)
SELECT
market_date,
max(daily_sales) AS daily_sales,
'Best Day' AS comment
FROM
daily_sales
UNION
SELECT
market_date,
min(daily_sales) AS daily_sales,
'Worst Day' AS comment
FROM daily_sales

52 changes: 49 additions & 3 deletions 03_homework/homework_5.sql
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Expand Up @@ -9,26 +9,62 @@ 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_product AS (
SELECT
DISTINCT vendor_id, product_id, original_price
FROM
vendor_inventory
)

SELECT
v.vendor_name, p.product_name,
vp.original_price * 5 * (SELECT count(*) FROM customer) AS total_sales
FROM
vendor_product vp JOIN vendor v on vp.vendor_id = v.vendor_id
JOIN product p ON vp.product_id = p.product_id
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 AS
SELECT
*,
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
)
SELECT
(SELECT max(product_id) + 1 FROM product),
'Apple Pie', '6"', 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 = 7


-- UPDATE
Expand All @@ -49,3 +85,13 @@ Finally, make sure you have a WHERE statement to update the right row,
When you have all of these components, you can run the update statement. */


UPDATE product_units
SET
current_quantity = COALESCE((SELECT quantity
FROM vendor_inventory vi
WHERE product_units.product_id = vi.product_id
GROUP by vi.product_id
HAVING market_date = max(market_date)
), 0)

SELECT * FROM product_units
6 changes: 6 additions & 0 deletions 03_homework/homework_6.md
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Expand Up @@ -6,3 +6,9 @@
<br>

**Write**: Reflect on your previous work and how you would adjust to include ethics and inequity components. Total length should be a few paragraphs, no more than one page.

As a software engineer working in a publication company, I would incorporate ethics into my work by ensuring the accuracy, privacy, and security of the metadata and sales data I handle. I would implement strict protocols to safeguard consumer information and respect data privacy laws such as GDPR. Transparency would be a key principle, informing stakeholders about data usage and obtaining necessary consents. I would also be responsible for ensuring that the data I collect, and share is accurate and unbiased, providing a reliable foundation for business decisions and maintaining the trust of both our company and our customers.

In addressing inequity components, I would focus on identifying and mitigating any biases in the data collection and analysis processes. I would ensure that the metadata and sales data represent a diverse range of books and authors, preventing any unintentional favoritism towards specific genres, authors, or demographics. Additionally, I would analyze the sales data to understand how different groups of consumers are impacted by various factors such as pricing and promotions. I would help create more inclusive and equitable business strategies that promote fairness and diversity in the marketplace.