<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Db

 * @subpackage Adapter

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Db2.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/** @see Zend_Db_Adapter_Pdo_Ibm */

require_once 'Zend/Db/Adapter/Pdo/Ibm.php';

/** @see Zend_Db_Statement_Pdo_Ibm */

require_once 'Zend/Db/Statement/Pdo/Ibm.php';

/**

 * @category   Zend

 * @package    Zend_Db

 * @subpackage Adapter

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Db_Adapter_Pdo_Ibm_Db2

{

    /**

     * @var Zend_Db_Adapter_Abstract

     */

    protected $_adapter = null;

    /**

     * Construct the data server class.

     *

     * It will be used to generate non-generic SQL

     * for a particular data server

     *

     * @param Zend_Db_Adapter_Abstract $adapter

     */

    public function __construct($adapter)

    {

        $this->_adapter = $adapter;

    }

    /**

     * Returns a list of the tables in the database.

     *

     * @return array

     */

    public function listTables()

    {

        $sql = "SELECT tabname "

        . "FROM SYSCAT.TABLES ";

        return $this->_adapter->fetchCol($sql);

    }

    /**

     * DB2 catalog lookup for describe table

     *

     * @param string $tableName

     * @param string $schemaName OPTIONAL

     * @return array

     */

    public function describeTable($tableName, $schemaName = null)

    {

        $sql = "SELECT DISTINCT c.tabschema, c.tabname, c.colname, c.colno,

                c.typename, c.default, c.nulls, c.length, c.scale,

                c.identity, tc.type AS tabconsttype, k.colseq

                FROM syscat.columns c

                LEFT JOIN (syscat.keycoluse k JOIN syscat.tabconst tc

                 ON (k.tabschema = tc.tabschema

                   AND k.tabname = tc.tabname

                   AND tc.type = 'P'))

                 ON (c.tabschema = k.tabschema

                 AND c.tabname = k.tabname

                 AND c.colname = k.colname)

            WHERE "

            . $this->_adapter->quoteInto('UPPER(c.tabname) = UPPER(?)', $tableName);

        if ($schemaName) {

            $sql .= $this->_adapter->quoteInto(' AND UPPER(c.tabschema) = UPPER(?)', $schemaName);

        }

        $sql .= " ORDER BY c.colno";

        $desc = array();

        $stmt = $this->_adapter->query($sql);

        /**

         * To avoid case issues, fetch using FETCH_NUM

         */

        $result = $stmt->fetchAll(Zend_Db::FETCH_NUM);

        /**

         * The ordering of columns is defined by the query so we can map

         * to variables to improve readability

         */

        $tabschema      = 0;

        $tabname        = 1;

        $colname        = 2;

        $colno          = 3;

        $typename       = 4;

        $default        = 5;

        $nulls          = 6;

        $length         = 7;

        $scale          = 8;

        $identityCol    = 9;

        $tabconstype    = 10;

        $colseq         = 11;

        foreach ($result as $key => $row) {

            list ($primary, $primaryPosition, $identity) = array(false, null, false);

            if ($row[$tabconstype] == 'P') {

                $primary = true;

                $primaryPosition = $row[$colseq];

            }

            /**

             * In IBM DB2, an column can be IDENTITY

             * even if it is not part of the PRIMARY KEY.

             */

            if ($row[$identityCol] == 'Y') {

                $identity = true;

            }

            $desc[$this->_adapter->foldCase($row[$colname])] = array(

            'SCHEMA_NAME'      => $this->_adapter->foldCase($row[$tabschema]),

            'TABLE_NAME'       => $this->_adapter->foldCase($row[$tabname]),

            'COLUMN_NAME'      => $this->_adapter->foldCase($row[$colname]),

            'COLUMN_POSITION'  => $row[$colno]+1,

            'DATA_TYPE'        => $row[$typename],

            'DEFAULT'          => $row[$default],

            'NULLABLE'         => (bool) ($row[$nulls] == 'Y'),

            'LENGTH'           => $row[$length],

            'SCALE'            => $row[$scale],

            'PRECISION'        => ($row[$typename] == 'DECIMAL' ? $row[$length] : 0),

            'UNSIGNED'         => false,

            'PRIMARY'          => $primary,

            'PRIMARY_POSITION' => $primaryPosition,

            'IDENTITY'         => $identity

            );

        }

        return $desc;

    }

    /**

     * Adds a DB2-specific LIMIT clause to the SELECT statement.

     *

     * @param string $sql

     * @param integer $count

     * @param integer $offset OPTIONAL

     * @throws Zend_Db_Adapter_Exception

     * @return string

     */

    public function limit($sql, $count, $offset = 0)

    {

        $count = intval($count);

        if ($count < 0) {

            /** @see Zend_Db_Adapter_Exception */

            require_once 'Zend/Db/Adapter/Exception.php';

            throw new Zend_Db_Adapter_Exception("LIMIT argument count=$count is not valid");

        } else {

            $offset = intval($offset);

            if ($offset < 0) {

                /** @see Zend_Db_Adapter_Exception */

                require_once 'Zend/Db/Adapter/Exception.php';

                throw new Zend_Db_Adapter_Exception("LIMIT argument offset=$offset is not valid");

            }

            if ($offset == 0 && $count > 0) {

                $limit_sql = $sql . " FETCH FIRST $count ROWS ONLY";

                return $limit_sql;

            }

            /**

             * DB2 does not implement the LIMIT clause as some RDBMS do.

             * We have to simulate it with subqueries and ROWNUM.

             * Unfortunately because we use the column wildcard "*",

             * this puts an extra column into the query result set.

             */

            $limit_sql = "SELECT z2.*

              FROM (

                  SELECT ROW_NUMBER() OVER() AS \"ZEND_DB_ROWNUM\", z1.*

                  FROM (

                      " . $sql . "

                  ) z1

              ) z2

              WHERE z2.zend_db_rownum BETWEEN " . ($offset+1) . " AND " . ($offset+$count);

        }

        return $limit_sql;

    }

    /**

     * DB2-specific last sequence id

     *

     * @param string $sequenceName

     * @return integer

     */

    public function lastSequenceId($sequenceName)

    {

        $sql = 'SELECT PREVVAL FOR '.$this->_adapter->quoteIdentifier($sequenceName).' AS VAL FROM SYSIBM.SYSDUMMY1';

        $value = $this->_adapter->fetchOne($sql);

        return $value;

    }

    /**

     * DB2-specific sequence id value

     *

     *  @param string $sequenceName

     *  @return integer

     */

    public function nextSequenceId($sequenceName)

    {

        $sql = 'SELECT NEXTVAL FOR '.$this->_adapter->quoteIdentifier($sequenceName).' AS VAL FROM SYSIBM.SYSDUMMY1';

        $value = $this->_adapter->fetchOne($sql);

        return $value;

    }

}