--This function returns true if the account with the given username (and, optionally,  password) exists, false otherwise.
function getAccount(username, password)
    local dbNode = getDatabaseHandler()
    if not dbNode then
        return false
    end

    local accountQuery
    if password then
        accountQuery = dbQuery(dbNode, "SELECT ID FROM accounts WHERE username = ? AND password = ?", username, password)
    else
        accountQuery = dbQuery(dbNode, "SELECT ID FROM accounts WHERE username = ?", username)
    end
    local accountResult, numRows = dbPoll(accountQuery, -1)
    dbFree(accountQuery)

    return (numRows > 0 and true) or false
end