📊 8-Week SQL Challenge Portfolio

A collection of end-to-end SQL case studies from Danny Ma's 8-Week SQL Challenge, engineered to solve real-world business problems using advanced relational database querying and analytical reporting.

---

🛠️ Tech Stack & Database Concepts

• Database Engine: PostgreSQL

• Core Concepts:

  • Multi-table Joins (INNER, LEFT, CROSS JOIN)
  • Data Aggregation & Grouping (GROUP BY, HAVING, Filtered Aggregations)
  • Window Functions (ROW_NUMBER(), DENSE_RANK(), RANK(), LEAD(), LAG())
  • Common Table Expressions (CTEs / WITH Clauses) & Subqueries
  • Conditional Business Logic (CASE WHEN)
  • Date/Time Parsing & Timestamps

---

📂 Case Study Tracker

#	Case Study	Business Focus	Status	Case Study & Solutions
1	Danny's Diner	Customer spending, visiting patterns & loyalty points	🟢 Complete	📖 README • 🛠️ setup.sql • 💻 solutions.sql
2	Pizza Runner	Delivery metrics, runner efficiency & operations	⚪ In Progress	Upcoming
3	Foodie-Fi	Subscription churn, onboarding & payment analysis	⚪ Backlog	Upcoming
4	Data Bank	Customer transactions, data allocation & storage	⚪ Backlog	Upcoming
5	Data Mart	Sales impact analysis & cleaning time-series data	⚪ Backlog	Upcoming
6	Clique Bait	E-commerce funnel, campaign conversion & tracking	⚪ Backlog	Upcoming
7	Balanced Tree Clothing	Retail sales, product revenue & transaction analysis	⚪ Backlog	Upcoming
8	Fresh Segments	Customer interest metrics & composition analysis	⚪ Backlog	Upcoming

---

🏗️ Repository Architecture

Each case study directory is structured as a self-contained module:

8-Week-SQL-Challenge/
│
├── README.md
│   └── Master project overview
│
└── Case Study 1 - Danny's Diner/
    ├── README.md
    │   └── Problem breakdown & business insights
    │
    ├── setup.sql
    │   └── Schema DDL and sample data insertion
    │
    └── solutions.sql
        └── Clean, executable PostgreSQL solutions

---

🚀 How to Run Locally

1. Clone the repository

git clone https://github.com/Omkesh-Bash/8-Week-SQL-Challenge.git

2. Navigate to the desired case study folder

cd "Case Study 1 - Danny's Diner"

3. Set up the database

Run setup.sql in your local PostgreSQL terminal or client, such as DBeaver or psql, to initialize the database schema and populate the tables.

4. Execute the solutions

Run solutions.sql to execute the queries and verify the expected outputs.

psql -d your_database -f setup.sql
psql -d your_database -f solutions.sql

---

🎯 Project Goals

This portfolio demonstrates practical SQL skills through progressively complex business problems, including:

• Customer behavior analysis
• Sales and revenue analysis
• Subscription and churn analysis
• Delivery and operational performance
• E-commerce funnel analysis
• Retail transaction analysis
• Customer segmentation
• Time-series data analysis
• Advanced SQL querying and reporting

---

📌 About the Challenge

The 8-Week SQL Challenge was created by Danny Ma to help data professionals strengthen their SQL skills through real-world case studies.

Each case study focuses on a different business scenario and requires analytical thinking, data exploration, and progressively advanced SQL techniques.