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‎.gitignore

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## Specific to this project:
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.env
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*.db
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*.sqlite3
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## Specific to Mac OS X:
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.DS_Store
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.AppleDouble
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.LSOverride
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# OS X thumbnails
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._*
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## Specific to Windows:
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# Windows image file caches
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Thumbs.db
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ehthumbs.db
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# Folder config file
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Desktop.ini
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## Specific to Ruby:
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*.gem
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*.rbc
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/.config
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/coverage/
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/InstalledFiles
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/pkg/
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/spec/reports/
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/test/tmp/
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/test/version_tmp/
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/tmp/
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## Ruby documentation cache and generated files:
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/.yardoc/
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/_yardoc/
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/doc/
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/rdoc/
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## Ruby environment normalisation:
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/.bundle/
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/lib/bundler/man/
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.rvmrc
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## Specific to Cloud9 IDE:
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.c9revisions
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.c9
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## Specific to Vim:
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[._]*.s[a-w][a-z]
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[._]s[a-w][a-z]
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*.un~
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Session.vim
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.netrwhist
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*~
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## Specific to Sublime Text:
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# Cache files for sublime text
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*.tmlanguage.cache
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*.tmPreferences.cache
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*.stTheme.cache
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# Workspace files are user-specific
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*.sublime-workspace
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# sftp configuration file
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sftp-config.json
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## Specific to RubyMotion:
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.dat*
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.repl_history
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build/

‎LICENSE

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The MIT License (MIT)
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Copyright (c) 2014 CodeUnion, Inc. <http://codeunion.io>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.

‎README.md

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# Example Database Schemas
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This repository contains a handful of example database schemas. We want this
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repository to do two things:
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1. Serve as a reference for common schema design patterns
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2. Give students more exposure to schema-level SQL, e.g.,
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`CREATE TABLE`, `CREATE UNIQUE INDEX`, and so on.
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## Format of This Repository
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Every schema is contained in its own directory. For example, the
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[blog_with_tags](blog_with_tags) directory contains a schema for a very basic
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blog with support for tagging blog posts. In this example, the schema itself is
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contained in a file named
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```text
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blog_with_tags.postgres.sql
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```
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which contains raw SQL `CREATE TABLE` statements that define the various tables,
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indexes, and associations that make up the database schema.
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The file is named `.postgres.sql` because the SQL statements contained inside
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follow PostgreSQL's dialect of SQL. Every database engine has its own "dialect"
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of SQL, whether the engine MySQL, SQLite3, Microsoft SQL Server, or Oracle.
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We'll be adding examples in other dialects as time goes on. If you want to
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help the process along, [we welcome pull requests][pull-request-url]
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## Schemas in This Repository
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### Blog With Tags
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The [blog_with_tags](blog_with_tags) schema models a basic blog where users can
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publish articles and tag them with arbitrary tags. It defines users, articles,
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and tags.
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### Blog With Likes
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The [blog_with_likes](blog_with_likes) schema models a basic blog where users
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can publish new articles or like already-published articles. It defines users,
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articles, and likes.
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### Question and Answer
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The [question_and_answer](question_and_answer) schema models a basic Q&A site
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a la Stack Overflow or Yahoo! Answers. It defines users, questions, answers,
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and voting.
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### Surveys
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The [surveys](surveys) schema models a website where users can create surveys
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for other users to fill out. It defines users, surveys, survey choices, and
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survey responses.
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### Reddit
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The [reddit](reddit) schema models a Reddit-like site where users submit links
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for other to vote and comment on. It defines users, link submissions, voting,
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and nested commenting.
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### Photo Gallery
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The [photo_gallery](photo_gallery) schema models a basic photo gallery. Users
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can create albums and upload photos to a specific album.
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### Hangman
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The [hangman](hangman) schema models a player vs. computer version of
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[letter-guessing game Hangman](http://en.wikipedia.org/wiki/Hangman_%28game%29).
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It defines users, games, turns, and phrases.
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### Tic Tac Toe
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The [tic_tac_toe](tic_tac_toe) schema models a collection of tic-tac-toe games.
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It defines users, games, and turns.
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[pull-request-url]: https://github.com/codeunion/examples-schema/pulls

‎blog_with_likes/blog_with_likes.postgres.sql

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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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email VARCHAR(255) NOT NULL,
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password_digest VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON users(email);
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CREATE TABLE articles (
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id SERIAL PRIMARY KEY,
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author_id INTEGER NOT NULL,
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title VARCHAR(255) NOT NULL,
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body TEXT NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (author_id) REFERENCES users(id)
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);
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CREATE INDEX ON articles(author_id);
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CREATE TABLE likes (
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id SERIAL PRIMARY KEY,
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article_id INTEGER NOT NULL,
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user_id INTEGER NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (article_id) REFERENCES articles(id),
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FOREIGN KEY (user_id) REFERENCES users(id)
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);
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CREATE UNIQUE INDEX ON likes(article_id, user_id);
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CREATE INDEX ON likes(user_id);

‎blog_with_tags/blog_with_tags.postgres.sql

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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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email VARCHAR(255) NOT NULL,
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password_digest VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON users(email);
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CREATE TABLE articles (
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id SERIAL PRIMARY KEY,
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author_id INTEGER NOT NULL,
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title VARCHAR(255) NOT NULL,
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body TEXT NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (author_id) REFERENCES users(id)
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);
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CREATE INDEX ON articles(author_id);
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CREATE TABLE tags (
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id SERIAL PRIMARY KEY,
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name VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON tags(name);
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CREATE TABLE taggings (
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id SERIAL PRIMARY KEY,
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article_id INTEGER NOT NULL,
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tag_id INTEGER NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (article_id) REFERENCES articles(id),
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FOREIGN KEY (tag_id) REFERENCES tags(id)
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);
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CREATE UNIQUE INDEX ON taggings(article_id, tag_id);
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CREATE INDEX ON taggings(tag_id);

‎hangman/hangman.postgres.sql

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-- In this schema, when a player initiates a new game, the computer would
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-- pick one of the entries from the `phrases` table as the phrase-to-guess.
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--
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-- Every turn or guess would result in a new entry in the `turns` table,
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-- containing the letter the player guessed for that turn.
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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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email VARCHAR(255) NOT NULL,
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password_digest VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON users(email);
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CREATE TABLE games (
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id SERIAL PRIMARY KEY,
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player_id INTEGER NOT NULL,
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phrase_id INTEGER NOT NULL,
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guess_limit INTEGER NOT NULL,
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completed_at TIMESTAMP,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (player_id) REFERENCES users(id),
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FOREIGN KEY (phrase_id) REFERENCES phrases(id)
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);
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CREATE INDEX ON games(player_id);
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CREATE TABLE phrases (
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id SERIAL PRIMARY KEY,
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body VARCHAR(255) NOT NULL
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)
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CREATE TABLE turns (
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id SERIAL PRIMARY KEY,
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game_id INTEGER NOT NULL,
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letter_guessed CHAR(1) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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FOREIGN KEY (game_id) REFERENCES games(id)
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);
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-- For a given game, a player can't guess the same letter twice.
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CREATE UNIQUE INDEX ON turns(game_id, letter_guessed);

‎photo_gallery/photo_gallery.postgres.sql

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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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email VARCHAR(255) NOT NULL,
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password_digest VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON users(email);
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CREATE TABLE albums (
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id SERIAL PRIMARY KEY,
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user_id INTEGER NOT NULL,
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name VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (user_id) REFERENCES users(id)
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);
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CREATE INDEX ON albums(user_id);
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CREATE TABLE photos (
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id SERIAL PRIMARY KEY,
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album_id INTEGER NOT NULL,
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filename VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (album_id) REFERENCES albums(id)
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);
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CREATE INDEX ON photos(album_id);

‎question_answer/question_answer.postgres.sql

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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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email VARCHAR(255) NOT NULL,
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username VARCHAR(255) NOT NULL,
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password_digest VARCHAR(255) NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL
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);
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CREATE UNIQUE INDEX ON users(email);
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CREATE UNIQUE INDEX ON users(username);
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CREATE TABLE questions (
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id SERIAL PRIMARY KEY,
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author_id INTEGER NOT NULL,
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best_answer_id INTEGER,
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title VARCHAR(255) NOT NULL,
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body TEXT NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (author_id) REFERENCES users(id),
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FOREIGN KEY (best_answer_id) REFERENCES answers(id)
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);
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CREATE INDEX ON questions(author_id);
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CREATE TABLE answers (
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id SERIAL PRIMARY KEY,
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author_id INTEGER NOT NULL,
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question_id INTEGER NOT NULL,
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body TEXT NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (author_id) REFERENCES users(id),
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FOREIGN KEY (question_id) REFERENCES questions(id)
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);
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CREATE UNIQUE INDEX ON answers(author_id, question_id);
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CREATE INDEX ON answers(question_id);
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CREATE TABLE answer_votes (
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id SERIAL PRIMARY KEY,
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answer_id INTEGER NOT NULL,
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voter_id INTEGER NOT NULL,
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score INTEGER NOT NULL,
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created_at TIMESTAMP NOT NULL,
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updated_at TIMESTAMP NOT NULL,
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FOREIGN KEY (answer_id) REFERENCES posts(id),
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FOREIGN KEY (voter_id) REFERENCES users(id)
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);
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CREATE UNIQUE INDEX ON answer_votes(answer_id, voter_id);
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CREATE INDEX ON answer_votes(voter_id);

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