/classes/Connection.php

<?php
class Connection
    {
        private $DOC_ROOT = 'D:/USR/apache/htdocs/s2.localhost';
        private $mysqli;
        private $config;

        /**
         * Method is called before object is serialized
         *
         * @return array
         */
        public function __sleep()
        {
            return array('DOC_ROOT', 'config');
        }

        /**
         * Method is called after object is unserialized
         */
        public function __wakeup()
        {
            $this->connect();
            $this->setCharset('utf8');
            $this->selectDb($this->config['dbname']);
        }

        /**
         *
         * @param array $config Parsed ini file
         * @param string $doc_root Path to document root of webserver (absolute)
         */
        public function __construct($config, $doc_root)
        {
            $this->DOC_ROOT = $doc_root;
            $this->setConfig($config);
            $this->connect();
            $this->setCharset('utf8');
            $this->selectDb($this->config['dbname']);
        }

        public function __destruct()
        {
            $this->close();
        }

        /**
         * Creates brand new mysqli object
         *
         * After using it, you must select database, because it's not selected
         */
        public function connect()
        {
            $this->mysqli = new mysqli('localhost', $this->config['username'],
                                                    $this->config['password']);
            if ($this->mysqli->connect_errno)
            {
                $error = 'Failed to connect to MySQL: ' . $this->mysqli->connect_error;
                include $this->DOC_ROOT . '/Phoenix_demo/templates/error.html.php';
                exit();
            }
        }

        /**
         * Closes current mysqli connection to db
         */
        public function close()
        {
            $this->mysqli->close();
        }

        /**
         * Sets $config of object
         *
         * @param array $config Parsed ini file
         */
        public function setConfig($config)
        {
            $this->config = $config;
            if (!$this->config)
            {
                $error = 'No config! Please, specify config before using this class';
                include $this->DOC_ROOT . '/Phoenix_demo/templates/error.html.php';
                exit();
            }
        }

        /**
         * Sets charset of db connection
         *
         * @param string $charset Legit mysql charset name
         */
        public function setCharset($charset)
        {
            if (!$this->mysqli->set_charset($charset))
            {
                $error = 'Unable to set Database connection encoding';
                include $this->DOC_ROOT .'/Phoenix_demo/templates/error.html.php';
                exit();
            }
        }

        /**
         * Selects database in current connection
         *
         * @param string $dbName Name of existing database
         */
        public function selectDb($dbName)
        {
            if (!$this->mysqli->select_db($dbName))
            {
                $error = 'Unable to locate selected database.';
                include $this->DOC_ROOT . '/Phoenix_demo/templates/error.html.php';
                exit();
            }
        }

        /**
         * Performs query  in mysql
         *
         * @param string $sql Sequence
         * @param string $errMes Message, which is displayed upon failure
         * @return array Result of sequence in form of numerical array
         */
        public function query($sql, $errMes)
        {
            $result = $this->mysqli->query($sql);
            if (!$result)
            {
                $error = $errMes;
                include $this->DOC_ROOT . '/Phoenix_demo/templates/error.html.php';
                exit();
            }
            return $result;
        }

        /**
         * Performs query in mysql, returns row
         *
         * @param string $sql Sequence
         * @param string $errMes Message, which is displayed upon failure
         * @return mixed First row from requested seqence in form of numerical array or NULL
         */
        public function queryRow($sql, $errMes)
        {
            $result = $this->mysqli->query($sql);
            if (!$result)
            {
                $error = $errMes;
                include $this->DOC_ROOT . '/Phoenix_demo/templates/error.html.php';
                exit();
            }
            return mysqli_fetch_row($result);
        }

        /**
         * Performs search of lowest and highest ids in `quotes` table
         * Saves them in referenced variables
         *
         * @param &int $min Reference to variable, where to save left border of interval
         * @param &int $max Reference to variable, where to save right border of interval
         */
        public function fetchInterval(&$min, &$max)
        {
            $sql = 'SELECT MIN(id), MAX(id) FROM `quotes`';
            $errMes = 'Error fetching quotes of Phoenix from db!';
            $row = $this->queryRow($sql, $errMes);
            $min = $row[0];
            $max = $row[1];
        }

        /**
         * Returns a random int in interval,
         * which is unique against given array $ids
         *
         * @param int $min Left border of interval
         * @param int $max Right border of interval
         * @param array $ids Already stored numbers
         * @return int
         */
        public function uniqueNum($min, $max, $ids)
        {
            do
            {
                //выбирает случайный номер цитаты
                $temp_id = mt_rand($min, $max);
            }
            //проверяет список номеров цитат на дубликаты
            while (array_search($temp_id, $ids) !== FALSE);
            return $temp_id;
        }

        /**
         * Return mysql_result, containing quote with given $id
         *
         * @param int $id ID of  quote
         * @return mixed Mysql_result or FALSE upon failure
         */
        public function fetchQuote($id)
        {
            $sql = "SELECT `quote` FROM `quotes` WHERE `id` = $id";
            $errMes = 'Error fetching quotes of Phoenix from db! ';
            $result = $this->query($sql, $errMes);
            if (mysqli_num_rows($result) === 0)
            {
                $result = false;
            }
            return $result;
        }
    }