*The assignment is to be done by yourself, do not turn in AI-generated work.*
You **will** need to create SQL queries on the first exam.
The following assumes you have gone through PostgreSQL instructions and have ran some queries on the `university` database.
Download the Assignment 1 distribution <ahref="https://ceres.cs.umd.edu/424/assign/assignment1Dist.tgz">here</a>.
The resulting files are:
1. populate.sql: The SQL script for creating the data.
1. queries.py: The file where to enter your answer
1. SQLTesting.py: File to be used for running the queries (in `queries.py`) against the database, and generate the file to be submitted.
1. Dockerfile: A modified Dockerfile for this project.
### Getting started
Start the container as in Assignment 0.
- Create a new database called `elections` and switch to it (see the PostgreSQL setup instructions).
- Run `\i populate.sql` to create and populate the tables.
Note that as usual, you do not *have* to use Docker. However, it might make things easier for you.
### Schema
The dataset contains results of `senate` and `presidential` elections for a subset of the years. For the `senate`, it contains only the statewide results from 1976 to 2018, whereas for the `presidential` elections, it contains county-level data going back to 2000.
The schema of the tables should be self-explanatory.
The data was collected from https://electionlab.mit.edu/data.
Some things to remember:
- The `special senate` elections are problematic. Typically senate elections take place every 6 years, with the two elections for a given state staggered. So generally speaking, any given year (say 2018), there would only be one senate election per state. However, because of special circumstances, there are
sometimes 2 elections in a given year for the same state. These two can be disambiguated based on the `specialelections` boolean flag in the database.
In many cases (especially for complex queries or queries involving
`max` or `min`), you will find it easier to create temporary tables
using the `with` construct. This also allows you to break down the full
query and makes it easier to debug.
You don't have to use the "hints" if you don't want to; there might
be simpler ways to solve the questions.
### Testing using SQLTesting.py
Build (`docker build --rm -t 424 .`) and run (`docker run -it -v $(pwd):/424 424`)
the container as before, then `cd /424` (inside the container).
You will be writing a series of queries to implement the prompts in
`queries.py`. Your answers (i.e., SQL queries) should be added to
`queries.py` file at the appropriate line. A simple query is provided
for the first answer to show you how it works. You are also provided
with a Python file `SQLTesting.py` for testing your answers.
- We recommend that you use `psql` to design your queries, and then paste the queries to the `queries.py` file, and confirm it works.
- SQLTesting takes quite a few options: use `python3 SQLTesting.py -h` to see the options.
- To get started with SQLTesting, do: `python3 SQLTesting.py -i` -- that will run each of the queries and show you your answer.
- Run your query for Question 1, for example: `python3 SQLTesting.py -q 1`.
-`-i` flag to SQLTesting will run all the queries, one at a time (waiting for you to press Enter after each query).
-**Note**: We will essentially run a modified version of `SQLTesting.py` that compares the returned answers against correct answers. So it imperative that `python3 SQLTesting.py` runs without errors.
### Notes/Errata
- Database changes **do not** persist across container restarts,
i.e. across distinct run commands. This is because database state is
stored in the container's file system, which is ephemeral. This should
not be an issue as `queries.py` is mounted from the distribution directory.
### Apple Silicon (M1, M2...) Macs
You can **use postgres directly** via **Homebrew**:
```
brew install postgresql@14
brew services restart postgresql@14
```
Before running `SQLTesting.py`, you also need to install `psycopg2`:
```
pip3 install psycopg2
```
## Submission Instructions
See `queries.py` for queries to write.
Submit your altered `queries.py` to Gradescope at <ahref="https://www.gradescope.com/courses/535193/assignments/2852219">Assignment 1</a>.
