<?php
/*
 *  $Id$
 *
 * 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.com>.
 */
Doctrine::autoload('Doctrine_Connection');
/**
 * Doctrine_Connection_Db2
 *
 * @package     Doctrine
 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @category    Object Relational Mapping
 * @link        www.phpdoctrine.com
 * @since       1.0
 * @version     $Revision$
 * @author      Konsta Vesterinen <kvesteri@cc.hut.fi>
 */
class Doctrine_Connection_Db2 extends Doctrine_Connection
{
    /**
     * Adds an driver-specific LIMIT clause to the query
     *
     * @param string $query         query to modify
     * @param integer $limit        limit the number of rows
     * @param integer $offset       start reading from given offset
     * @return string               the modified query
     */
    public function modifyLimitQuery($query, $limit, $offset)
    {
        if ($limit <= 0)
            return $query;

        if ($offset == 0) {
            return $query . ' FETCH FIRST '. $limit .' ROWS ONLY';
        } else {
            $sqlPieces = explode('from', $query);
            $select = $sqlPieces[0];
            $table = $sqlPieces[1];

            $col = explode('select', $select);

            $sql = 'WITH OFFSET AS(' . $select . ', ROW_NUMBER() ' .
               'OVER(ORDER BY ' . $col[1] . ') AS dctrn_rownum FROM ' . $table . ')' .
               $select . 'FROM OFFSET WHERE dctrn_rownum BETWEEN ' . $offset .
                   'AND ' . ($offset + $limit - 1);
            return $sql;
        }
    }
}
