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

Added my answers to the Homework_4.sql file

What did you learn from the changes you have made?

From the COALESCE question, we learned how to handle and replace NULL values within concatenated strings for cleaner data presentation. The Windowed Functions task taught us to use functions like ROW_NUMBER() to assign sequential numbers to rows within partitions of data, allowing us to track and filter specific records such as the most recent visit. In the String Manipulations exercise, we used functions like SUBSTR() and INSTR() to extract and clean substrings within a column, effectively handling and standardizing inconsistent data entries. Lastly, the UNION query demonstrated how to combine results from multiple queries to display distinct aggregate data, such as the highest and lowest sales days, using CTEs and window functions for clear and precise data analysis.

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?

I did get a bunch of errors as I was trying to find the correct queries, to overcoming these challenges I needed to do a combination careful testing, and iterative refinement of queries as well as more research to understand the SQL functions better.

How were these changes tested?

I tested this code on DB Browser for SQLite

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

Checklist

• I can confirm that my changes are working as intended