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

What did you learn from the changes you have made?

I learn about the usage of Windowed functions to various useful use cases. also learn about the different types of Insert, Update mechanisms.

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

for the UNION question. I think that can be done with simple case statement as well.
Also, the Current_Timestamp is not working when execution the entire section so I used 'now' with mili seconds different between first insert and manual insert. to work won the latest update.

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

I found one challenge for INSERT question. where it was specified and current_timestamp. but if we are executing the query really first between two Insert query, then the delete one is not working properly and milliseconds are not consider in Sqllite current_timestamp

How were these changes tested?

I executed all of them at once to see any error in execution or not. Also individually executing every query or queries to check the outcome.

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

for the Last Update query I assume that last quantity for a product in vendor_inventory table means latest quantity with respect to latest market_date.

Checklist

• I can confirm that my changes are working as intended