EN605.607.81.SP22_ASDM_Project/backend_database_specification.md

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# Backend Database Specification
The backend will use sqlite to store all state for storing players (and their
IDs, and paired state), and games in progress.
## Table definitions
```
// enable foreign_keys restrictions
PRAGMA foreign_keys = ON;
// fields should be self explanatory for the players table
CREATE TABLE players (id INTEGER PRIMARY KEY NOT NULL,
date_added TEXT NOT NULL,
game_id INTEGER,
FOREIGN KEY(game_id) REFERENCES games(id) ON DELETE CASCADE);
// "cyan_player" and "magenta_player" should correspond to an existing entry in
// table "players".
// "board" is as explained in backend_protocol_specification.md
// "status" is "0" for cyan's turn, "1" for magenta's turn, "2" for cyan won,
// "3" for magenta won, "4" for draw.
CREATE TABLE games (id INTEGER PRIMARY KEY NOT NULL,
cyan_player INTEGER UNIQUE NOT NULL,
magenta_player INTEGER UNIQUE NOT NULL,
date_changed TEXT NOT NULL,
board TEXT NOT NULL,
status INTEGER NOT NULL,
FOREIGN KEY(cyan_player) REFERENCES players (id),
FOREIGN KEY(magenta_player) REFERENCES players (id));
```
"date" entries are used for garbage collection of the database. A predefined
length of time will be used to cleanup stale entries. Whenever an entry in the
"games" table is updated, the "date" entry will be updated as well.