What changes are you trying to make? (e.g. Adding or removing code, refactoring existing code, adding reports)

I added my answers to Homework 5

What did you learn from the changes you have made?

I learned how to manipulate and manage data in SQL using various commands such as ALTER TABLE, UPDATE, and COALESCE. Specifically, I learned how to add new columns to existing tables and update them based on complex queries that involve subqueries and joins.

Was there another approach you were thinking about making? If so, what approach(es) were you thinking of?

Were there any challenges? If so, what issue(s) did you face? How did you overcome it?

One challenge was ensuring that the subquery for retrieving the last quantity accurately linked to the correct product without duplicating or missing any records. I overcame this by carefully structuring the subquery to filter by both product_id and market_date, ensuring that I retrieved the most recent quantity for each product. Testing each part of the query incrementally helped me identify any issues early on.

How were these changes tested?

I tested the changes by running SELECT queries on the product_units table after the UPDATE operation to verify that the current_quantity values were populated correctly. I also cross-referenced the results with the vendor_inventory table to ensure that the latest quantities matched the expected values. Additionally, I checked edge cases where products might not have any quantity to ensure the COALESCE function worked as intended.

A reference to a related issue in your repository (if applicable)

Checklist

• I can confirm that my changes are working as intended