Write SQL queries to solve a mystery.
A Mystery in Fiftyville
The CS50 Duck has been stolen! The town of Fiftyville has called upon you to solve the mystery of the stolen duck. Authorities believe that the thief stole the duck and then, shortly afterwards, took a flight out of town with the help of an accomplice. Your goal is to identify:
- Who the thief is,
- What city the thief escaped to, and
- Who the thief’s accomplice is who helped them escape
All you know is that the theft took place on July 28, 2021 and that it took place on Humphrey Street.
How will you go about solving this mystery? The Fiftyville authorities have taken some of the town’s records from around the time of the theft and prepared a SQLite database for you,
fiftyville.db, which contains tables of data from around the town. You can query that table using SQL
SELECT queries to access the data of interest to you. Using just the information in the database, your task is to solve the mystery.
Log into code.cs50.io, click on your terminal window, and execute
cd by itself. You should find that your terminal window’s prompt resembles the below:
in order to download a ZIP called
fiftyville.zip into your codespace.
to create a folder called
fiftyville. You no longer need the ZIP file, so you can execute
and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded.
followed by Enter to move yourself into (i.e., open) that directory. Your prompt should now resemble the below.
ls by itself, and you should see a few files:
answers.txt fiftyville.db log.sql
If you run into any trouble, follow these same steps again and see if you can determine where you went wrong!
For this problem, equally as important as solving the mystery itself is the process that you use to solve the mystery. In
log.sql, keep a log of all SQL queries that you run on the database. Above each query, label each with a comment (in SQL, comments are any lines that begin with
--) describing why you’re running the query and/or what information you’re hoping to get out of that particular query. You can use comments in the log file to add additional notes about your thought process as you solve the mystery: ultimately, this file should serve as evidence of the process you used to identify the thief!
As you write your queries, you may notice that some of them can become quite complex. To help keep your queries readable, see principles of good style at sqlstyle.guide. The indentation section may be particularly helpful!
Once you solve the mystery, complete each of the lines in
answers.txt by filling in the name of the thief, the city that the thief escaped to, and the name of the thief’s accomplice who helped them escape town. (Be sure not to change any of the existing text in the file or to add any other lines to the file!)
Ultimately, you should submit both your
Note: This walkthrough is about a different infamous crime in Fiftyville, which took place on Chamberlin Street. Authorities are certain the most recent theft took place on Humphrey Street. The database they’ve given you has been updated to include the
sqlite3 fiftyville.dbto begin running queries on the database.
- While running
.tableswill list all of the tables in the database.
- While running
.schema TABLE_NAME, where
TABLE_NAMEis the name of a table in the database, will show you the
CREATE TABLEcommand used to create the table. This can be helpful for knowing which columns to query!
- While running
- You may find it helpful to start with the
crime_scene_reportstable. Start by looking for a crime scene report that matches the date and the location of the crime.
- See this SQL keywords reference for some SQL syntax that may be helpful!
Execute the below to evaluate the correctness of your code using
How to Submit
In your terminal, execute the below to submit your work.
Inspired by another case over at SQL City.