A collection of completed case studies from Data With Danny's 8 Week SQL Challenge.
The following case studies have been curated by Danny Ma and are available on https://8weeksqlchallenge.com. Queries in each completed case study are written using the PostgreSQL Database Management System.
| Case Study | Description | Status |
|---|---|---|
| #1: Danny's Diner | Danny’s Diner is in the first few months of operation but needs assistance using their data to help them keep the business afloat. | Completed |
| #2: Pizza Runner | Pizza Runner requires further assistance cleaning data and applying basic calculations to better direct runners and optimise business operations. | Completed |
| #3: Foodie-Fi | Foodie-Fi, a subscription streaming service for food-related content, wants to utilize data to better understand customer retention, churn, and growth. | Completed |
| #4: Data Bank | Digital bank and data storage platform Data Bank needs help analyzing their data to calculate metrics, growth, and forecast smarter for future developments. | Parts A & B Complete |
| #5: Data Mart | After making large scale supply changes to packaging methods, Data Mart wants help quantifying the impact to their sales performance. | Completed |
| #6: Clique Bait | Online seafood retailer, Clique Bait, wants help analyzing data to calculate campaign effectiveness and website interactions by customers. | In - Progress |
SQL techniques used include:
- conditional statements (
CASE,NULLIF,COALESCE,IN) - common table expressions
- subqueries and nested queries
- window functions (
SUM,COUNT,AVG,RANK(),DENSE_RANK(),LAG,LEAD,ROW_NUMBER) GENERATE_SERIES- date and time functions (
INTERVAL,AGE,EXTRACT,DATE_TRUNC) CONCAT,CAST, and aliasing- array functions (
UNNEST,STRING_TO_ARRAY,STRING_AGG,ARRAY_LENGTH)