Assignment two

[PSulf]

What changes are you trying to make?

• Created a complete logical model for a bookstore database including all required entities (employees, orders, sales, customers, books)
• Implemented two versions of customer address architecture (Type 1 and Type 2 SCD)
• Added employee shift functionality to the ERD
• Developed SQL solutions for COALESCE, window functions, string manipulations, and UNION operations
• Included visual ERD diagrams in both conceptual and logical formats

What did you learn from the changes you have made?

• The importance of slowly changing dimensions in data warehousing
• How to properly model time-sensitive data like employee shifts
• Practical applications of window functions for customer purchase analysis
• The difference between logical and conceptual data models
• How to handle NULL values effectively in SQL queries

Was there another approach you were thinking about making?

For the customer address problem, I considered:

1. Using a single address table with version numbers instead of Type 2's effective dating
2. Implementing a hybrid Type 1/Type 2 approach where some fields overwrite and others track history
3. Creating a separate address history table instead of combining current/historical addresses

Were there any challenges?

Main challenges included:

1. Merge conflicts in Assignment2.md - resolved by carefully reviewing both versions and maintaining all requirements
2. Determining optimal table relationships - overcame by sketching multiple ERD versions
3. Window function syntax - solved through SQL documentation review
4. Rebasing Git history - fixed by following force-push protocols after thorough verification

How were these changes tested?

• ERDs were validated against normalization rules
• SQL queries were tested in DB Browser for SQLite
• All solutions were verified against the assignment rubric
• Final output was checked in both GitHub and local environment

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

N/A

Checklist

• I can confirm that my changes are working as intended

[JzfL]

Well done! 70/70