Doctrine_Connection_Mssql with optimized modifyLimitQuery()

Doctrine_Connection_Mssql.php

<?php
/*
 *  $Id: Mssql.php 5804 2009-06-02 19:52:42Z jwage $
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.phpdoctrine.org>.
 */

/**
 * Doctrine_Connection_Mssql
 *
 * @package     Doctrine
 * @subpackage  Connection
 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @author      Konsta Vesterinen <kvesteri@cc.hut.fi>
 * @author      Lukas Smith <smith@pooteeweet.org> (PEAR MDB2 library)
 * @version     $Revision: 5804 $
 * @link        www.phpdoctrine.org
 * @since       1.0
 */
class Doctrine_Connection_Mssql extends Doctrine_Connection
{
    /**
     * @var string $driverName                  the name of this connection driver
     */
    protected $driverName = 'Mssql';

    /**
     * the constructor
     *
     * @param Doctrine_Manager $manager
     * @param PDO $pdo                          database handle
     */
    public function __construct(Doctrine_Manager $manager, $adapter)
    {
        // initialize all driver options
        $this->supported = array(
                          'sequences'             => 'emulated',
                          'indexes'               => true,
                          'affected_rows'         => true,
                          'transactions'          => true,
                          'summary_functions'     => true,
                          'order_by_text'         => true,
                          'current_id'            => 'emulated',
                          'limit_queries'         => 'emulated',
                          'LOBs'                  => true,
                          'replace'               => 'emulated',
                          'sub_selects'           => true,
                          'auto_increment'        => true,
                          'primary_key'           => true,
                          'result_introspection'  => true,
                          'prepared_statements'   => 'emulated',
                          );

        parent::__construct($manager, $adapter);
    }

    /**
     * quoteIdentifier
     * Quote a string so it can be safely used as a table / column name
     *
     * Quoting style depends on which database driver is being used.
     *
     * @param string $identifier    identifier name to be quoted
     * @param bool   $checkOption   check the 'quote_identifier' option
     *
     * @return string  quoted identifier string
     */
    public function quoteIdentifier($identifier, $checkOption = false)
    {
        if ($checkOption && ! $this->getAttribute(Doctrine::ATTR_QUOTE_IDENTIFIER)) {
            return $identifier;
        }

        if (strpos($identifier, '.') !== false) {
            $parts = explode('.', $identifier);
            $quotedParts = array();
            foreach ($parts as $p) {
                $quotedParts[] = $this->quoteIdentifier($p);
            }

            return implode('.', $quotedParts);
        }

        return '[' . str_replace(']', ']]', $identifier) . ']';
    }

    /**
     * Adds an adapter-specific LIMIT clause to the SELECT statement.
     * Inspired by Doctrine2 DBAL
     *
     * Known issues :
     *  - Remove the "DISTINCT" keyword
     *  - Not compatible with subqueries used like WHERE ... IN (SELECT ... LIMIT x OFFSET y)
     *
     * @param string $query
     * @param mixed $limit
     * @param mixed $offset
     * @link https://github.com/doctrine/dbal/blob/master/lib/Doctrine/DBAL/Platforms/MsSqlPlatform.php#L607
     * @link http://www.toosweettobesour.com/2010/09/16/doctrine-1-2-mssql-alternative-limitpaging/
     * @return string
     */
    public function modifyLimitQuery($query, $limit = false, $offset = false, $isManip = false)
    {
        $limit = intval($limit);
        $offset = intval($offset);

        if ($limit > 0) {

            if ($offset < 0) {
                throw new Doctrine_Connection_Exception("LIMIT argument offset=$offset is not valid");
            }

            if ($offset == 0) {
                $query = preg_replace('/^SELECT(\s+DISTINCT)?\s/i', "SELECT TOP $limit ", $query);
            } else {
                $over = stristr($query, 'ORDER BY');

                if (!$over) {
                    $over = 'ORDER BY (SELECT 0)';
                } else {
                    // Remove ORDER BY clause from $query
                    $query = stristr($query, 'ORDER BY', true);
                }

                // Remove the first SELECT from query
                $query = preg_replace('/^SELECT(\s+DISTINCT)?\s/i', '', $query);

                $start = $offset + 1;
                $end = $offset + $limit;

                $query = "SELECT * FROM (SELECT ROW_NUMBER() OVER ($over) AS [DOCTRINE_ROWNUM], $query) AS [doctrine_tbl] WHERE [DOCTRINE_ROWNUM] BETWEEN $start AND $end";
            }
        }

        return $query;
    }

    /**
     * return version information about the server
     *
     * @param bool   $native  determines if the raw version string should be returned
     * @return mixed array/string with version information or MDB2 error object
     */
    public function getServerVersion($native = false)
    {
        if ($this->serverInfo) {
            $serverInfo = $this->serverInfo;
        } else {
            $query      = 'SELECT @@VERSION';
            $serverInfo = $this->fetchOne($query);
        }
        // cache server_info
        $this->serverInfo = $serverInfo;
        if ( ! $native) {
            if (preg_match('/([0-9]+)\.([0-9]+)\.([0-9]+)/', $serverInfo, $tmp)) {
                $serverInfo = array(
                    'major' => $tmp[1],
                    'minor' => $tmp[2],
                    'patch' => $tmp[3],
                    'extra' => null,
                    'native' => $serverInfo,
                );
            } else {
                $serverInfo = array(
                    'major' => null,
                    'minor' => null,
                    'patch' => null,
                    'extra' => null,
                    'native' => $serverInfo,
                );
            }
        }
        return $serverInfo;
    }

    /**
     * Checks if there's a sequence that exists.
     *
     * @param  string $seq_name     The sequence name to verify.
     * @return boolean              The value if the table exists or not
     */
    public function checkSequence($seqName)
    {
        $query = 'SELECT * FROM ' . $seqName;
        try {
            $this->exec($query);
        } catch(Doctrine_Connection_Exception $e) {
            if ($e->getPortableCode() == Doctrine::ERR_NOSUCHTABLE) {
                return false;
            }

            throw $e;
        }
        return true;
    }
}