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<?php

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**

 * The PEAR DB driver for PHP's mysqli extension

 * for interacting with MySQL databases

 *

 * PHP versions 4 and 5

 *

 * LICENSE: This source file is subject to version 3.0 of the PHP license

 * that is available through the world-wide-web at the following URI:

 * http://www.php.net/license/3_0.txt.  If you did not receive a copy of

 * the PHP License and are unable to obtain it through the web, please

 * send a note to license@php.net so we can mail you a copy immediately.

 *

 * @category   Database

 * @package    DB

 * @author     Daniel Convissor <danielc@php.net>

 * @copyright  1997-2005 The PHP Group

 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0

 * @version    CVS: $Id: mysqli.php,v 1.3 2006-12-14 15:04:28 jp_milcent Exp $

 * @link       http://pear.php.net/package/DB

 */

/**

 * Obtain the DB_common class so it can be extended from

 */

require_once 'DB/common.php';

/**

 * The methods PEAR DB uses to interact with PHP's mysqli extension

 * for interacting with MySQL databases

 *

 * This is for MySQL versions 4.1 and above.  Requires PHP 5.

 *

 * Note that persistent connections no longer exist.

 *

 * These methods overload the ones declared in DB_common.

 *

 * @category   Database

 * @package    DB

 * @author     Daniel Convissor <danielc@php.net>

 * @copyright  1997-2005 The PHP Group

 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0

 * @version    Release: 1.7.6

 * @link       http://pear.php.net/package/DB

 * @since      Class functional since Release 1.6.3

 */

class DB_mysqli extends DB_common

{

    // {{{ properties

    /**

     * The DB driver type (mysql, oci8, odbc, etc.)

     * @var string

     */

    var $phptype = 'mysqli';

    /**

     * The database syntax variant to be used (db2, access, etc.), if any

     * @var string

     */

    var $dbsyntax = 'mysqli';

    /**

     * The capabilities of this DB implementation

     *

     * The 'new_link' element contains the PHP version that first provided

     * new_link support for this DBMS.  Contains false if it's unsupported.

     *

     * Meaning of the 'limit' element:

     *   + 'emulate' = emulate with fetch row by number

     *   + 'alter'   = alter the query

     *   + false     = skip rows

     *

     * @var array

     */

    var $features = array(

        'limit'         => 'alter',

        'new_link'      => false,

        'numrows'       => true,

        'pconnect'      => false,

        'prepare'       => false,

        'ssl'           => true,

        'transactions'  => true,

    );

    /**

     * A mapping of native error codes to DB error codes

     * @var array

     */

    var $errorcode_map = array(

        1004 => DB_ERROR_CANNOT_CREATE,

        1005 => DB_ERROR_CANNOT_CREATE,

        1006 => DB_ERROR_CANNOT_CREATE,

        1007 => DB_ERROR_ALREADY_EXISTS,

        1008 => DB_ERROR_CANNOT_DROP,

        1022 => DB_ERROR_ALREADY_EXISTS,

        1044 => DB_ERROR_ACCESS_VIOLATION,

        1046 => DB_ERROR_NODBSELECTED,

        1048 => DB_ERROR_CONSTRAINT,

        1049 => DB_ERROR_NOSUCHDB,

        1050 => DB_ERROR_ALREADY_EXISTS,

        1051 => DB_ERROR_NOSUCHTABLE,

        1054 => DB_ERROR_NOSUCHFIELD,

        1061 => DB_ERROR_ALREADY_EXISTS,

        1062 => DB_ERROR_ALREADY_EXISTS,

        1064 => DB_ERROR_SYNTAX,

        1091 => DB_ERROR_NOT_FOUND,

        1100 => DB_ERROR_NOT_LOCKED,

        1136 => DB_ERROR_VALUE_COUNT_ON_ROW,

        1142 => DB_ERROR_ACCESS_VIOLATION,

        1146 => DB_ERROR_NOSUCHTABLE,

        1216 => DB_ERROR_CONSTRAINT,

        1217 => DB_ERROR_CONSTRAINT,

    );

    /**

     * The raw database connection created by PHP

     * @var resource

     */

    var $connection;

    /**

     * The DSN information for connecting to a database

     * @var array

     */

    var $dsn = array();

    /**

     * Should data manipulation queries be committed automatically?

     * @var bool

     * @access private

     */

    var $autocommit = true;

    /**

     * The quantity of transactions begun

     *

     * {@internal  While this is private, it can't actually be designated

     * private in PHP 5 because it is directly accessed in the test suite.}}

     *

     * @var integer

     * @access private

     */

    var $transaction_opcount = 0;

    /**

     * The database specified in the DSN

     *

     * It's a fix to allow calls to different databases in the same script.

     *

     * @var string

     * @access private

     */

    var $_db = '';

    /**

     * Array for converting MYSQLI_*_FLAG constants to text values

     * @var    array

     * @access public

     * @since  Property available since Release 1.6.5

     */

    var $mysqli_flags = array(

        MYSQLI_NOT_NULL_FLAG        => 'not_null',

        MYSQLI_PRI_KEY_FLAG         => 'primary_key',

        MYSQLI_UNIQUE_KEY_FLAG      => 'unique_key',

        MYSQLI_MULTIPLE_KEY_FLAG    => 'multiple_key',

        MYSQLI_BLOB_FLAG            => 'blob',

        MYSQLI_UNSIGNED_FLAG        => 'unsigned',

        MYSQLI_ZEROFILL_FLAG        => 'zerofill',

        MYSQLI_AUTO_INCREMENT_FLAG  => 'auto_increment',

        MYSQLI_TIMESTAMP_FLAG       => 'timestamp',

        MYSQLI_SET_FLAG             => 'set',

        // MYSQLI_NUM_FLAG             => 'numeric',  // unnecessary

        // MYSQLI_PART_KEY_FLAG        => 'multiple_key',  // duplicatvie

        MYSQLI_GROUP_FLAG           => 'group_by'

    );

    /**

     * Array for converting MYSQLI_TYPE_* constants to text values

     * @var    array

     * @access public

     * @since  Property available since Release 1.6.5

     */

    var $mysqli_types = array(

        MYSQLI_TYPE_DECIMAL     => 'decimal',

        MYSQLI_TYPE_TINY        => 'tinyint',

        MYSQLI_TYPE_SHORT       => 'int',

        MYSQLI_TYPE_LONG        => 'int',

        MYSQLI_TYPE_FLOAT       => 'float',

        MYSQLI_TYPE_DOUBLE      => 'double',

        // MYSQLI_TYPE_NULL        => 'DEFAULT NULL',  // let flags handle it

        MYSQLI_TYPE_TIMESTAMP   => 'timestamp',

        MYSQLI_TYPE_LONGLONG    => 'bigint',

        MYSQLI_TYPE_INT24       => 'mediumint',

        MYSQLI_TYPE_DATE        => 'date',

        MYSQLI_TYPE_TIME        => 'time',

        MYSQLI_TYPE_DATETIME    => 'datetime',

        MYSQLI_TYPE_YEAR        => 'year',

        MYSQLI_TYPE_NEWDATE     => 'date',

        MYSQLI_TYPE_ENUM        => 'enum',

        MYSQLI_TYPE_SET         => 'set',

        MYSQLI_TYPE_TINY_BLOB   => 'tinyblob',

        MYSQLI_TYPE_MEDIUM_BLOB => 'mediumblob',

        MYSQLI_TYPE_LONG_BLOB   => 'longblob',

        MYSQLI_TYPE_BLOB        => 'blob',

        MYSQLI_TYPE_VAR_STRING  => 'varchar',

        MYSQLI_TYPE_STRING      => 'char',

        MYSQLI_TYPE_GEOMETRY    => 'geometry',

    );

    // }}}

    // {{{ constructor

    /**

     * This constructor calls <kbd>$this->DB_common()</kbd>

     *

     * @return void

     */

    function DB_mysqli()

    {

        $this->DB_common();

    }

    // }}}

    // {{{ connect()

    /**

     * Connect to the database server, log in and open the database

     *

     * Don't call this method directly.  Use DB::connect() instead.

     *

     * PEAR DB's mysqli driver supports the following extra DSN options:

     *   + When the 'ssl' $option passed to DB::connect() is true:

     *     + key      The path to the key file.

     *     + cert     The path to the certificate file.

     *     + ca       The path to the certificate authority file.

     *     + capath   The path to a directory that contains trusted SSL

     *                 CA certificates in pem format.

     *     + cipher   The list of allowable ciphers for SSL encryption.

     *

     * Example of how to connect using SSL:

     * <code>

     * require_once 'DB.php';

     *

     * $dsn = array(

     *     'phptype'  => 'mysqli',

     *     'username' => 'someuser',

     *     'password' => 'apasswd',

     *     'hostspec' => 'localhost',

     *     'database' => 'thedb',

     *     'key'      => 'client-key.pem',

     *     'cert'     => 'client-cert.pem',

     *     'ca'       => 'cacert.pem',

     *     'capath'   => '/path/to/ca/dir',

     *     'cipher'   => 'AES',

     * );

     *

     * $options = array(

     *     'ssl' => true,

     * );

     *

     * $db =& DB::connect($dsn, $options);

     * if (PEAR::isError($db)) {

     *     die($db->getMessage());

     * }

     * </code>

     *

     * @param array $dsn         the data source name

     * @param bool  $persistent  should the connection be persistent?

     *

     * @return int  DB_OK on success. A DB_Error object on failure.

     */

    function connect($dsn, $persistent = false)

    {

        if (!PEAR::loadExtension('mysqli')) {

            return $this->raiseError(DB_ERROR_EXTENSION_NOT_FOUND);

        }

        $this->dsn = $dsn;

        if ($dsn['dbsyntax']) {

            $this->dbsyntax = $dsn['dbsyntax'];

        }

        $ini = ini_get('track_errors');

        ini_set('track_errors', 1);

        $php_errormsg = '';

        if ($this->getOption('ssl') === true) {

            $init = mysqli_init();

            mysqli_ssl_set(

                $init,

                empty($dsn['key'])    ? null : $dsn['key'],

                empty($dsn['cert'])   ? null : $dsn['cert'],

                empty($dsn['ca'])     ? null : $dsn['ca'],

                empty($dsn['capath']) ? null : $dsn['capath'],

                empty($dsn['cipher']) ? null : $dsn['cipher']

            );

            if ($this->connection = @mysqli_real_connect(

                    $init,

                    $dsn['hostspec'],

                    $dsn['username'],

                    $dsn['password'],

                    $dsn['database'],

                    $dsn['port'],

                    $dsn['socket']))

            {

                $this->connection = $init;

            }

        } else {

            $this->connection = @mysqli_connect(

                $dsn['hostspec'],

                $dsn['username'],

                $dsn['password'],

                $dsn['database'],

                $dsn['port'],

                $dsn['socket']

            );

        }

        ini_set('track_errors', $ini);

        if (!$this->connection) {

            if (($err = @mysqli_connect_error()) != '') {

                return $this->raiseError(DB_ERROR_CONNECT_FAILED,

                                         null, null, null,

                                         $err);

            } else {

                return $this->raiseError(DB_ERROR_CONNECT_FAILED,

                                         null, null, null,

                                         $php_errormsg);

            }

        }

        if ($dsn['database']) {

            $this->_db = $dsn['database'];

        }

        return DB_OK;

    }

    // }}}

    // {{{ disconnect()

    /**

     * Disconnects from the database server

     *

     * @return bool  TRUE on success, FALSE on failure

     */

    function disconnect()

    {

        $ret = @mysqli_close($this->connection);

        $this->connection = null;

        return $ret;

    }

    // }}}

    // {{{ simpleQuery()

    /**

     * Sends a query to the database server

     *

     * @param string  the SQL query string

     *

     * @return mixed  + a PHP result resrouce for successful SELECT queries

     *                + the DB_OK constant for other successful queries

     *                + a DB_Error object on failure

     */

    function simpleQuery($query)

    {

        $ismanip = DB::isManip($query);

        $this->last_query = $query;

        $query = $this->modifyQuery($query);

        if ($this->_db) {

            if (!@mysqli_select_db($this->connection, $this->_db)) {

                return $this->mysqliRaiseError(DB_ERROR_NODBSELECTED);

            }

        }

        if (!$this->autocommit && $ismanip) {

            if ($this->transaction_opcount == 0) {

                $result = @mysqli_query($this->connection, 'SET AUTOCOMMIT=0');

                $result = @mysqli_query($this->connection, 'BEGIN');

                if (!$result) {

                    return $this->mysqliRaiseError();

                }

            }

            $this->transaction_opcount++;

        }

        $result = @mysqli_query($this->connection, $query);

        if (!$result) {

            return $this->mysqliRaiseError();

        }

        if (is_object($result)) {

            return $result;

        }

        return DB_OK;

    }

    // }}}

    // {{{ nextResult()

    /**

     * Move the internal mysql result pointer to the next available result.

     *

     * This method has not been implemented yet.

     *

     * @param resource $result a valid sql result resource

     * @return false

     * @access public

     */

    function nextResult($result)

    {

        return false;

    }

    // }}}

    // {{{ fetchInto()

    /**

     * Places a row from the result set into the given array

     *

     * Formating of the array and the data therein are configurable.

     * See DB_result::fetchInto() for more information.

     *

     * This method is not meant to be called directly.  Use

     * DB_result::fetchInto() instead.  It can't be declared "protected"

     * because DB_result is a separate object.

     *

     * @param resource $result    the query result resource

     * @param array    $arr       the referenced array to put the data in

     * @param int      $fetchmode how the resulting array should be indexed

     * @param int      $rownum    the row number to fetch (0 = first row)

     *

     * @return mixed  DB_OK on success, NULL when the end of a result set is

     *                 reached or on failure

     *

     * @see DB_result::fetchInto()

     */

    function fetchInto($result, &$arr, $fetchmode, $rownum = null)

    {

        if ($rownum !== null) {

            if (!@mysqli_data_seek($result, $rownum)) {

                return null;

            }

        }

        if ($fetchmode & DB_FETCHMODE_ASSOC) {

            $arr = @mysqli_fetch_array($result, MYSQLI_ASSOC);

            if ($this->options['portability'] & DB_PORTABILITY_LOWERCASE && $arr) {

                $arr = array_change_key_case($arr, CASE_LOWER);

            }

        } else {

            $arr = @mysqli_fetch_row($result);

        }

        if (!$arr) {

            return null;

        }

        if ($this->options['portability'] & DB_PORTABILITY_RTRIM) {

            /*

             * Even though this DBMS already trims output, we do this because

             * a field might have intentional whitespace at the end that

             * gets removed by DB_PORTABILITY_RTRIM under another driver.

             */

            $this->_rtrimArrayValues($arr);

        }

        if ($this->options['portability'] & DB_PORTABILITY_NULL_TO_EMPTY) {

            $this->_convertNullArrayValuesToEmpty($arr);

        }

        return DB_OK;

    }

    // }}}

    // {{{ freeResult()

    /**

     * Deletes the result set and frees the memory occupied by the result set

     *

     * This method is not meant to be called directly.  Use

     * DB_result::free() instead.  It can't be declared "protected"

     * because DB_result is a separate object.

     *

     * @param resource $result  PHP's query result resource

     *

     * @return bool  TRUE on success, FALSE if $result is invalid

     *

     * @see DB_result::free()

     */

    function freeResult($result)

    {

        return @mysqli_free_result($result);

    }

    // }}}

    // {{{ numCols()

    /**

     * Gets the number of columns in a result set

     *

     * This method is not meant to be called directly.  Use

     * DB_result::numCols() instead.  It can't be declared "protected"

     * because DB_result is a separate object.

     *

     * @param resource $result  PHP's query result resource

     *

     * @return int  the number of columns.  A DB_Error object on failure.

     *

     * @see DB_result::numCols()

     */

    function numCols($result)

    {

        $cols = @mysqli_num_fields($result);

        if (!$cols) {

            return $this->mysqliRaiseError();

        }

        return $cols;

    }

    // }}}

    // {{{ numRows()

    /**

     * Gets the number of rows in a result set

     *

     * This method is not meant to be called directly.  Use

     * DB_result::numRows() instead.  It can't be declared "protected"

     * because DB_result is a separate object.

     *

     * @param resource $result  PHP's query result resource

     *

     * @return int  the number of rows.  A DB_Error object on failure.

     *

     * @see DB_result::numRows()

     */

    function numRows($result)

    {

        $rows = @mysqli_num_rows($result);

        if ($rows === null) {

            return $this->mysqliRaiseError();

        }

        return $rows;

    }

    // }}}

    // {{{ autoCommit()

    /**

     * Enables or disables automatic commits

     *

     * @param bool $onoff  true turns it on, false turns it off

     *

     * @return int  DB_OK on success.  A DB_Error object if the driver

     *               doesn't support auto-committing transactions.

     */

    function autoCommit($onoff = false)

    {

        // XXX if $this->transaction_opcount > 0, we should probably

        // issue a warning here.

        $this->autocommit = $onoff ? true : false;

        return DB_OK;

    }

    // }}}

    // {{{ commit()

    /**

     * Commits the current transaction

     *

     * @return int  DB_OK on success.  A DB_Error object on failure.

     */

    function commit()

    {

        if ($this->transaction_opcount > 0) {

            if ($this->_db) {

                if (!@mysqli_select_db($this->connection, $this->_db)) {

                    return $this->mysqliRaiseError(DB_ERROR_NODBSELECTED);

                }

            }

            $result = @mysqli_query($this->connection, 'COMMIT');

            $result = @mysqli_query($this->connection, 'SET AUTOCOMMIT=1');

            $this->transaction_opcount = 0;

            if (!$result) {

                return $this->mysqliRaiseError();

            }

        }

        return DB_OK;

    }

    // }}}

    // {{{ rollback()

    /**

     * Reverts the current transaction

     *

     * @return int  DB_OK on success.  A DB_Error object on failure.

     */

    function rollback()

    {

        if ($this->transaction_opcount > 0) {

            if ($this->_db) {

                if (!@mysqli_select_db($this->connection, $this->_db)) {

                    return $this->mysqliRaiseError(DB_ERROR_NODBSELECTED);

                }

            }

            $result = @mysqli_query($this->connection, 'ROLLBACK');

            $result = @mysqli_query($this->connection, 'SET AUTOCOMMIT=1');

            $this->transaction_opcount = 0;

            if (!$result) {

                return $this->mysqliRaiseError();

            }

        }

        return DB_OK;

    }

    // }}}

    // {{{ affectedRows()

    /**

     * Determines the number of rows affected by a data maniuplation query

     *

     * 0 is returned for queries that don't manipulate data.

     *

     * @return int  the number of rows.  A DB_Error object on failure.

     */

    function affectedRows()

    {

        if (DB::isManip($this->last_query)) {

            return @mysqli_affected_rows($this->connection);

        } else {

            return 0;

        }

     }

    // }}}

    // {{{ nextId()

    /**

     * Returns the next free id in a sequence

     *

     * @param string  $seq_name  name of the sequence

     * @param boolean $ondemand  when true, the seqence is automatically

     *                            created if it does not exist

     *

     * @return int  the next id number in the sequence.

     *               A DB_Error object on failure.

     *

     * @see DB_common::nextID(), DB_common::getSequenceName(),

     *      DB_mysqli::createSequence(), DB_mysqli::dropSequence()

     */

    function nextId($seq_name, $ondemand = true)

    {

        $seqname = $this->getSequenceName($seq_name);

        do {

            $repeat = 0;

            $this->pushErrorHandling(PEAR_ERROR_RETURN);

            $result = $this->query('UPDATE ' . $seqname

                                   . ' SET id = LAST_INSERT_ID(id + 1)');

            $this->popErrorHandling();

            if ($result === DB_OK) {

                // COMMON CASE

                $id = @mysqli_insert_id($this->connection);

                if ($id != 0) {

                    return $id;

                }

                // EMPTY SEQ TABLE

                // Sequence table must be empty for some reason,

                // so fill it and return 1

                // Obtain a user-level lock

                $result = $this->getOne('SELECT GET_LOCK('

                                        . "'${seqname}_lock', 10)");

                if (DB::isError($result)) {

                    return $this->raiseError($result);

                }

                if ($result == 0) {

                    return $this->mysqliRaiseError(DB_ERROR_NOT_LOCKED);

                }

                // add the default value

                $result = $this->query('REPLACE INTO ' . $seqname

                                       . ' (id) VALUES (0)');

                if (DB::isError($result)) {

                    return $this->raiseError($result);

                }

                // Release the lock

                $result = $this->getOne('SELECT RELEASE_LOCK('

                                        . "'${seqname}_lock')");

                if (DB::isError($result)) {

                    return $this->raiseError($result);

                }

                // We know what the result will be, so no need to try again

                return 1;

            } elseif ($ondemand && DB::isError($result) &&

                $result->getCode() == DB_ERROR_NOSUCHTABLE)

            {

                // ONDEMAND TABLE CREATION

                $result = $this->createSequence($seq_name);

                // Since createSequence initializes the ID to be 1,

                // we do not need to retrieve the ID again (or we will get 2)

                if (DB::isError($result)) {

                    return $this->raiseError($result);

                } else {

                    // First ID of a newly created sequence is 1

                    return 1;

                }

            } elseif (DB::isError($result) &&

                      $result->getCode() == DB_ERROR_ALREADY_EXISTS)

            {

                // BACKWARDS COMPAT

                // see _BCsequence() comment

                $result = $this->_BCsequence($seqname);

                if (DB::isError($result)) {

                    return $this->raiseError($result);

                }

                $repeat = 1;

            }

        } while ($repeat);

        return $this->raiseError($result);

    }

    /**

     * Creates a new sequence

     *

     * @param string $seq_name  name of the new sequence

     *

     * @return int  DB_OK on success.  A DB_Error object on failure.

     *

     * @see DB_common::createSequence(), DB_common::getSequenceName(),

     *      DB_mysqli::nextID(), DB_mysqli::dropSequence()

     */

    function createSequence($seq_name)

    {

        $seqname = $this->getSequenceName($seq_name);

        $res = $this->query('CREATE TABLE ' . $seqname

                            . ' (id INTEGER UNSIGNED AUTO_INCREMENT NOT NULL,'

                            . ' PRIMARY KEY(id))');

        if (DB::isError($res)) {

            return $res;

        }

        // insert yields value 1, nextId call will generate ID 2

        return $this->query("INSERT INTO ${seqname} (id) VALUES (0)");

    }

    // }}}

    // {{{ dropSequence()

    /**

     * Deletes a sequence

     *

     * @param string $seq_name  name of the sequence to be deleted

     *

     * @return int  DB_OK on success.  A DB_Error object on failure.

     *

     * @see DB_common::dropSequence(), DB_common::getSequenceName(),

     *      DB_mysql::nextID(), DB_mysql::createSequence()

     */

    function dropSequence($seq_name)

    {

        return $this->query('DROP TABLE ' . $this->getSequenceName($seq_name));

    }

    // }}}

    // {{{ _BCsequence()

    /**

     * Backwards compatibility with old sequence emulation implementation

     * (clean up the dupes)

     *

     * @param string $seqname  the sequence name to clean up

     *

     * @return bool  true on success.  A DB_Error object on failure.

     *

     * @access private

     */

    function _BCsequence($seqname)

    {

        // Obtain a user-level lock... this will release any previous

        // application locks, but unlike LOCK TABLES, it does not abort

        // the current transaction and is much less frequently used.

        $result = $this->getOne("SELECT GET_LOCK('${seqname}_lock',10)");

        if (DB::isError($result)) {

            return $result;

        }

        if ($result == 0) {

            // Failed to get the lock, can't do the conversion, bail

            // with a DB_ERROR_NOT_LOCKED error

            return $this->mysqliRaiseError(DB_ERROR_NOT_LOCKED);

        }

        $highest_id = $this->getOne("SELECT MAX(id) FROM ${seqname}");

        if (DB::isError($highest_id)) {

            return $highest_id;

        }

        // This should kill all rows except the highest

        // We should probably do something if $highest_id isn't

        // numeric, but I'm at a loss as how to handle that...

        $result = $this->query('DELETE FROM ' . $seqname

                               . " WHERE id <> $highest_id");

        if (DB::isError($result)) {

            return $result;

        }

        // If another thread has been waiting for this lock,

        // it will go thru the above procedure, but will have no

        // real effect

        $result = $this->getOne("SELECT RELEASE_LOCK('${seqname}_lock')");

        if (DB::isError($result)) {

            return $result;

        }

        return true;

    }

    // }}}

    // {{{ quoteIdentifier()

    /**

     * Quotes a string so it can be safely used as a table or column name

     *

     * MySQL can't handle the backtick character (<kbd>`</kbd>) in

     * table or column names.

     *

     * @param string $str  identifier name to be quoted

     *

     * @return string  quoted identifier string

     *

     * @see DB_common::quoteIdentifier()

     * @since Method available since Release 1.6.0

     */

    function quoteIdentifier($str)

    {

        return '`' . $str . '`';

    }

    // }}}

    // {{{ escapeSimple()

    /**

     * Escapes a string according to the current DBMS's standards

     *

     * @param string $str  the string to be escaped

     *

     * @return string  the escaped string

     *

     * @see DB_common::quoteSmart()

     * @since Method available since Release 1.6.0

     */

    function escapeSimple($str)

    {

        return @mysqli_real_escape_string($this->connection, $str);

    }

    // }}}

    // {{{ modifyLimitQuery()

    /**

     * Adds LIMIT clauses to a query string according to current DBMS standards

     *

     * @param string $query   the query to modify

     * @param int    $from    the row to start to fetching (0 = the first row)

     * @param int    $count   the numbers of rows to fetch

     * @param mixed  $params  array, string or numeric data to be used in

     *                         execution of the statement.  Quantity of items

     *                         passed must match quantity of placeholders in

     *                         query:  meaning 1 placeholder for non-array

     *                         parameters or 1 placeholder per array element.

     *

     * @return string  the query string with LIMIT clauses added

     *

     * @access protected

     */

    function modifyLimitQuery($query, $from, $count, $params = array())

    {

        if (DB::isManip($query)) {

            return $query . " LIMIT $count";

        } else {

            return $query . " LIMIT $from, $count";

        }

    }

    // }}}

    // {{{ mysqliRaiseError()

    /**

     * Produces a DB_Error object regarding the current problem

     *

     * @param int $errno  if the error is being manually raised pass a

     *                     DB_ERROR* constant here.  If this isn't passed

     *                     the error information gathered from the DBMS.

     *

     * @return object  the DB_Error object

     *

     * @see DB_common::raiseError(),

     *      DB_mysqli::errorNative(), DB_common::errorCode()

     */

    function mysqliRaiseError($errno = null)

    {

        if ($errno === null) {

            if ($this->options['portability'] & DB_PORTABILITY_ERRORS) {

                $this->errorcode_map[1022] = DB_ERROR_CONSTRAINT;

                $this->errorcode_map[1048] = DB_ERROR_CONSTRAINT_NOT_NULL;

                $this->errorcode_map[1062] = DB_ERROR_CONSTRAINT;

            } else {

                // Doing this in case mode changes during runtime.

                $this->errorcode_map[1022] = DB_ERROR_ALREADY_EXISTS;

                $this->errorcode_map[1048] = DB_ERROR_CONSTRAINT;

                $this->errorcode_map[1062] = DB_ERROR_ALREADY_EXISTS;

            }

            $errno = $this->errorCode(mysqli_errno($this->connection));

        }

        return $this->raiseError($errno, null, null, null,

                                 @mysqli_errno($this->connection) . ' ** ' .

                                 @mysqli_error($this->connection));

    }

    // }}}

    // {{{ errorNative()

    /**

     * Gets the DBMS' native error code produced by the last query

     *

     * @return int  the DBMS' error code

     */

    function errorNative()

    {

        return @mysqli_errno($this->connection);

    }

    // }}}

    // {{{ tableInfo()

    /**

     * Returns information about a table or a result set

     *

     * @param object|string  $result  DB_result object from a query or a

     *                                 string containing the name of a table.

     *                                 While this also accepts a query result

     *                                 resource identifier, this behavior is

     *                                 deprecated.

     * @param int            $mode    a valid tableInfo mode

     *

     * @return array  an associative array with the information requested.

     *                 A DB_Error object on failure.

     *

     * @see DB_common::setOption()

     */

    function tableInfo($result, $mode = null)

    {

        if (is_string($result)) {

            /*

             * Probably received a table name.

             * Create a result resource identifier.

             */

            $id = @mysqli_query($this->connection,

                                "SELECT * FROM $result LIMIT 0");

            $got_string = true;

        } elseif (isset($result->result)) {

            /*

             * Probably received a result object.

             * Extract the result resource identifier.

             */

            $id = $result->result;

            $got_string = false;

        } else {

            /*

             * Probably received a result resource identifier.

             * Copy it.

             * Deprecated.  Here for compatibility only.

             */

            $id = $result;

            $got_string = false;

        }

        if (!is_a($id, 'mysqli_result')) {

            return $this->mysqliRaiseError(DB_ERROR_NEED_MORE_DATA);

        }

        if ($this->options['portability'] & DB_PORTABILITY_LOWERCASE) {

            $case_func = 'strtolower';

        } else {

            $case_func = 'strval';

        }

        $count = @mysqli_num_fields($id);

        $res   = array();

        if ($mode) {