Assignment-two SQL Stephanie Shishis

[StephanieShishis]

UofT-DSI | SQL- Assignment 2

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

I further advanced my SQL query skills by modifying tables using inserts and deletes. I also was able to have queries that were able to handle null values using coalesce and used window functions like ROW_NUMBER().

What did you learn from the changes you have made?

I learned that coalesce is a really important function to deal with missing data, which is really applicable to real datasets (like my own) which may have null values. Additionally, learning how cross joins can expand data.

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

I though about using a case statement in Q1 to handle null values but coalesce was more efficient.

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

One of the main challenges I faced was with Q9, where creating the product units table failed because the table already existed and it threw an error when I ran it multiple times to double check my code. I solved this by using DROP TABLE IF EXISTS to ensure the table was removed before creating it. (I deleted this before submission). The other big challenge was just remembering all the query techniques which involved a lot of going back to the notes and checking my data.

How were these changes tested?

I tested each query in the SQL environment and ensure it did not throw any errors when it ran.

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

N/A

Checklist

• [YES] I can confirm that my changes are working as intended

[khsergvl]

Great attempt, reviewed. Try to play with git flows to better understand how does it work.