Lab 09: SQL Joins and Relations

Today we introduced Joins and Relations, which we'll be implementing using SQL.

Your lab TODOs today will require you to write SQL queries and add associated data to those queries in the server.js file, though you need to have an understanding at this point as to how everything is working together to accomplish our full functionality.

Submission Instructions

When you are finished with lab, follow these steps to submit your work. Create one Pull Request (aka: "PR") from your Forked repo to the CF repo with your changes, and you'll each submit that same PR link in Canvas.

Ensure that all your local changes are committed, and pushed to your origin repo.
Visit the origin repo on github.com, and ensure that all of your completed work has been merged to master via Pull Requests within your repo.
Create a new PR from your Fork to the CF repo and ensure the branches look correct.
Fill in the template based on the text box prompts:
Write a good descriptive summary of your changes: 1. Be sure to include how much time you spent on it, and who you worked with. 1. Briefly reflect on and summarize your process.
When you create the PR, it will have a unique URL. Copy this link, share with your partner, and paste it into the assignment submission form in Canvas. Both the driver and the navigator will submit the same PR link.

Learning Objectives

Understand how objects in a database can be interrelated with foreign keys
Have familiarity with queries using SQL that select data from across multiple tables
Have familiarity with different relationships in database tables

Resources

SQLBolt -- Interactive SQL Tutorial
SQL Cheat Sheet
Query String Primer

Getting started (DO THIS AFTER CLONING YOUR FORK)

cd starter-code to change dirs to the starter code directory
Ensure that you have your postgres server running, using the alias that we set up in lecture: pgstart

You will need to drop the table that we created yesterday in postgres!
To do so, start postgres in the terminal using the psql command
Once you're in the postgres shell, enter DROP TABLE articles; to remove the table from your local DB
Leave the shell open so you can check on your new tables in the upcoming setup steps!

In a new terminal window, run the following command from the starter code dir: bin/loadarticles

This command is a local executable in the bin/ directory (feel free to read the code, but do not get hung up on it if you don't know what's going on...)
It will create a connection with your local postgres db, read the contents of hackerIpsum.json, and then load authors into an authors table, and articles into an articles table with a reference to the author of each article (using the foreign key)
This executable also relies on the loadDB.js file in the lib/ directory (feel free to read the code!).

In your postgres shell:

Run select count(*) from articles;
- The output should read that you now have 250 records in the articles table.
Then run select * from authors;
- The output should read each of the five author records to your with their respective data

You're ready to go!

Feature Tasks

Don't forget to set your conString!

User Stories: MVP

As a developer, I want article data to persist with SQL, so that I can store more, faster and have more query flexibility.
As a developer, I want to be able to verify that the CRUD routes on my application are all properly functional.

This means you'll want to be able to do full CRUD on articles in the database. You'll have to use SQL to make a table for articles (and clear out the table for troubleshooting), with a class-level method attached to the constructor function (because it does not apply to any single instance). Then teach each article instance how to write or update itself to the database, or delete itself, via instance methods (available for use as needed in the code).

Crucially, you'll need to trace through the app logic, and all those callback functions to determine WHEN is the right time to load data, or convert JSON.

Look through the TODOs, which signify areas of the code with varying levels of completeness, and focus initially on writing correct SQL. Once you complete the TODOs, follow the instructions in the adjacent CRUD-testing.md doc to verify that everything works.

Rubric

Criteria	Pts
Meets all Assignment Reqs	6
Uses idiomatic code style	3
Follows proper Git workflow	1
Total	10

daltlc / 09-joins_and_relations