8 Week SQL Challenge (PostgreSQL)

This repository contains my solutions and case study write-ups for Danny Ma's 8 Week SQL Challenge. I am using PostgreSQL to solve complex, real-world business problems ranging from transactional data cleaning to advanced customer analytics and subscription metrics.

📚 Table of Contents

• Case Study #1: Danny's Diner
• Case Study #2: Pizza Runner
• Case Study #3: Foodie-Fi
• Case Study #4: Data Bank
• Case Study #5: Data Mart
• Case Study #6: Clique Bait
• Case Study #7: Balanced Tree Clothing Co
• Case Study #8: Fresh Segments

🛠️ Technical Environment

• Database: PostgreSQL
• Tools: DBeaver / Notepad++
• Key SQL Concepts Applied:
  • Common Table Expressions (CTEs)
  • Window Functions (RANK(), DENSE_RANK(), ROW_NUMBER(), LEAD(), LAG())
  • Data Cleansing & Type Casting (NULLIF, CASE WHEN, CAST)
  • Complex Joins & Subqueries

🚀 How to Run the Code

1. Clone this repository to your local machine: git clone https://github.com/jbonells/sql-8-week-challenge.git
2. Open your preferred PostgreSQL client (e.g., pgAdmin or DBeaver).
3. Navigate to the specific case study folder (e.g., Case Study #1 - Danny's Diner/) and execute the schema.sql file to set up the database and tables.
4. Run the queries in solutions.sql to explore the data and review the findings.
5. Check insights.md to understand my solutions.