Database Component Design
Alex Kossey

1. Overview

	The database component consists of a single PHP file that provides
	functions for interacting with the MySQL database. Originally, the plan was
	to provide a PHP file that replaced all MySQL queries with essentially
	equivalent PHP functions. However, the database component as it stands now
	provides more abstract functionality: it provides functions for wiping the
	whole database, inserting votes, retrieving all the election data, etc.

	The database that resides in the MySQL database consists of three separate
	tables: one to keep track of the types of each question on the ballot (for
	easy access by the data visualization component), one to keep track of
	which students have already voted, and one to keep track of the responses
	of the ballot. Note that although inserting a vote involves recording the
	name of the voter in the "already voted" database, the name of the voter
	and the voter's response are stored in completely different locations and
	thus aren't connected with each other after the vote is placed.

2. Interface

	The database component consists basically of seven functions in the
	DatabaseInterface.php file: db_wipeDatabase, db_connect, db_createTable,
	db_insertIntoTable, db_insertVote, db_getQuestionTypes, and
	db_getCurrentElecResults. The first four of these functions are only called
	by the Server Initialization component. The Election Administration
	component inserts information into the database with db_insertVote. The
	Data Visualization and exporting component retrieves the necessary
	information from the database with the final two functions.

3. Function Descriptions

	Descriptions of the functions themselves appear in the comments to the
	DatabaseInterface.php file; these descriptions basically paraphrase the
	ones in the file.

	db_connect: Takes the database server name, username, and password
	(constants in a constants file) and connects to the appropriate database in
	the MySQL database.

	db_wipeDatabase: Clears the database so that a new election can be stored.
	Just deletes all three of the tables so that they can be recreated when a
	new election begins.

	db_createTable: Takes a name of a table and an array specifying information
	about all the columns that should go in the table. Creates this new table
	based on the information given in the array. This array itself contains
	arrays holding columns names, column types, and column sizes so that the
	table can be appropriately formatted.

	db_insertIntoTable: Takes a table name and an array of values to insert
	into columns of a row in that table. Inserts this information into a row of
	the given table.

	db_insertVote: Takes a voter name and an array of voting info (an array
	mapping ballot question names to ballot question answers). Checks in the
	voter table to check if this voter has already voted. If so, they cannot
	vote again. Otherwise, it uses db_insertIntoTable to insert the voting
	information into the database.

	db_getQuestionTypes: Returns an array mapping question name to question
	type (just takes the contents of the question types table and returns
	them).

	db_getCurrentElecResults: Returns the current results of the election as a
	two-dimensional array. Each row in the two-dimensional array is an array
	consisting of one voter's responses to the ballot questions, so each row is
	a mapping from ballot question to voter response.