Mainframe Override

You've caught wind of an EmptyStack Solutions plan to break down the city's public transportation system! Someone on a popular online forum has bragged about much money they're going to make by investing in EmptyStack's latest model of self-driving taxi, claiming, "My dad works there and he's got some serious inside intel." Hack into the mainframe again to sabotage their project before all the city's trains and buses grind to a halt!

Getting Started

Use psql to run the provided init.sql file, which will create a local database named mainframe_override and populate it with some tables.

• forum_posts contains all the posts written on the online forum.
• forum_accounts contains information about the online forum accounts.
• emptystack_accounts contains credentials for EmptyStack Solutions employee accounts.

Instructions

Just like the previous mainframe workshop, your goal is to provide the correct admin credentials to node mainframe -stop in order to shut down the project.

In order to access EmptyStack's internal data, you will have to find an employee's credentials and log in via node mainframe. Getting that information will require some detective work!

Your first clue: you know that the forum post was made in April 2048, and the author mentioned something about EmptyStack and their dad, who shares the same last name and is also an active participant in the forum.

As you explore the mainframe_override database, write your SQL queries in submission.sql. Use -- to comment your thoughts and observations.

Walkthrough

Use psql to explore the tables in mainframe_override. That first clue is enough for you to figure out the rest! If you would like a more guided approach, or you just want to focus on practicing SQL, feel free to follow the steps below.

See walkthrough

1. Get the username of the person who made the post about EmptyStack in forum_posts.
2. Get the last name of the person associated with that username in forum_accounts.
3. Find all other accounts with the same last name.
4. Find all accounts in emptystack_accounts with the same last name.
5. There will only be one EmptyStack employee with a forum account. Use their credentials to access node mainframe, which will output a new sql file for you to run.
6. Find the message in emptystack_messages that mentions a project involving self-driving taxis. That message is sent from an admin account and also reveals the project code.
7. Get the credentials for the admin account from emptystack_accounts.
8. Get the ID of the project from emptystack_projects.
9. Use that information to stop the project: node mainframe -stop!

Submission

Please submit the link to your public GitHub repository.