sqlsrv.php

Aller à la documentation de ce fichier.

<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Database
 *
 * @copyright   Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * SQL Server database driver
 *
 * @package     Joomla.Platform
 * @subpackage  Database
 * @see         http://msdn.microsoft.com/en-us/library/cc296152(SQL.90).aspx
 * @since       12.1
 */
class JDatabaseDriverSqlsrv extends JDatabaseDriver
{
        /**
         * The name of the database driver.
         *
         * @var    string
         * @since  12.1
         */
        public $name = 'sqlsrv';

        /**
         * The character(s) used to quote SQL statement names such as table names or field names,
         * etc.  The child classes should define this as necessary.  If a single character string the
         * same character is used for both sides of the quoted name, else the first character will be
         * used for the opening quote and the second for the closing quote.
         *
         * @var    string
         * @since  12.1
         */
        protected $nameQuote = '[]';

        /**
         * The null or zero representation of a timestamp for the database driver.  This should be
         * defined in child classes to hold the appropriate value for the engine.
         *
         * @var    string
         * @since  12.1
         */
        protected $nullDate = '1900-01-01 00:00:00';

        /**
         * @var    string  The minimum supported database version.
         * @since  12.1
         */
        protected static $dbMinimum = '10.50.1600.1';

        /**
         * Test to see if the SQLSRV connector is available.
         *
         * @return  boolean  True on success, false otherwise.
         *
         * @since   12.1
         */
        public static function isSupported()
        {
                return (function_exists('sqlsrv_connect'));
        }

        /**
         * Constructor.
         *
         * @param   array  $options  List of options used to configure the connection
         *
         * @since   12.1
         */
        public function __construct($options)
        {
                // Get some basic values from the options.
                $options['host'] = (isset($options['host'])) ? $options['host'] : 'localhost';
                $options['user'] = (isset($options['user'])) ? $options['user'] : '';
                $options['password'] = (isset($options['password'])) ? $options['password'] : '';
                $options['database'] = (isset($options['database'])) ? $options['database'] : '';
                $options['select'] = (isset($options['select'])) ? (bool) $options['select'] : true;

                // Finalize initialisation
                parent::__construct($options);
        }

        /**
         * Destructor.
         *
         * @since   12.1
         */
        public function __destruct()
        {
                $this->disconnect();
        }

        /**
         * Connects to the database if needed.
         *
         * @return  void  Returns void if the database connected successfully.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function connect()
        {
                if ($this->connection)
                {
                        return;
                }

                // Build the connection configuration array.
                $config = array(
                        'Database' => $this->options['database'],
                        'uid' => $this->options['user'],
                        'pwd' => $this->options['password'],
                        'CharacterSet' => 'UTF-8',
                        'ReturnDatesAsStrings' => true);

                // Make sure the SQLSRV extension for PHP is installed and enabled.
                if (!function_exists('sqlsrv_connect'))
                {
                        throw new RuntimeException('PHP extension sqlsrv_connect is not available.');
                }

                // Attempt to connect to the server.
                if (!($this->connection = @ sqlsrv_connect($this->options['host'], $config)))
                {
                        throw new RuntimeException('Database sqlsrv_connect failed');
                }

                // Make sure that DB warnings are not returned as errors.
                sqlsrv_configure('WarningsReturnAsErrors', 0);

                // If auto-select is enabled select the given database.
                if ($this->options['select'] && !empty($this->options['database']))
                {
                        $this->select($this->options['database']);
                }
        }

        /**
         * Disconnects the database.
         *
         * @return  void
         *
         * @since   12.1
         */
        public function disconnect()
        {
                // Close the connection.
                if (is_resource($this->connection))
                {
                        foreach ($this->disconnectHandlers as $h)
                        {
                                call_user_func_array($h, array( &$this));
                        }

                        sqlsrv_close($this->connection);
                }

                $this->connection = null;
        }

        /**
         * Get table constraints
         *
         * @param   string  $tableName  The name of the database table.
         *
         * @return  array  Any constraints available for the table.
         *
         * @since   12.1
         */
        protected function getTableConstraints($tableName)
        {
                $this->connect();

                $query = $this->getQuery(true);

                $this->setQuery(
                        'SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = ' . $query->quote($tableName)
                );

                return $this->loadColumn();
        }

        /**
         * Rename constraints.
         *
         * @param   array   $constraints  Array(strings) of table constraints
         * @param   string  $prefix       A string
         * @param   string  $backup       A string
         *
         * @return  void
         *
         * @since   12.1
         */
        protected function renameConstraints($constraints = array(), $prefix = null, $backup = null)
        {
                $this->connect();

                foreach ($constraints as $constraint)
                {
                        $this->setQuery('sp_rename ' . $constraint . ',' . str_replace($prefix, $backup, $constraint));
                        $this->execute();
                }
        }

        /**
         * Method to escape a string for usage in an SQL statement.
         *
         * The escaping for MSSQL isn't handled in the driver though that would be nice.  Because of this we need
         * to handle the escaping ourselves.
         *
         * @param   string   $text   The string to be escaped.
         * @param   boolean  $extra  Optional parameter to provide extra escaping.
         *
         * @return  string  The escaped string.
         *
         * @since   12.1
         */
        public function escape($text, $extra = false)
        {
                $result = addslashes($text);
                $result = str_replace("\'", "''", $result);
                $result = str_replace('\"', '"', $result);
                $result = str_replace('\/', '/', $result);

                if ($extra)
                {
                        // We need the below str_replace since the search in sql server doesn't recognize _ character.
                        $result = str_replace('_', '[_]', $result);
                }

                return $result;
        }

        /**
         * Determines if the connection to the server is active.
         *
         * @return  boolean  True if connected to the database engine.
         *
         * @since   12.1
         */
        public function connected()
        {
                // TODO: Run a blank query here
                return true;
        }

        /**
         * Drops a table from the database.
         *
         * @param   string   $tableName  The name of the database table to drop.
         * @param   boolean  $ifExists   Optionally specify that the table must exist before it is dropped.
         *
         * @return  JDatabaseDriverSqlsrv  Returns this object to support chaining.
         *
         * @since   12.1
         */
        public function dropTable($tableName, $ifExists = true)
        {
                $this->connect();

                $query = $this->getQuery(true);

                if ($ifExists)
                {
                        $this->setQuery(
                                'IF EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = ' . $query->quote($tableName) . ') DROP TABLE ' . $tableName
                        );
                }
                else
                {
                        $this->setQuery('DROP TABLE ' . $tableName);
                }

                $this->execute();

                return $this;
        }

        /**
         * Get the number of affected rows for the previous executed SQL statement.
         *
         * @return  integer  The number of affected rows.
         *
         * @since   12.1
         */
        public function getAffectedRows()
        {
                $this->connect();

                return sqlsrv_rows_affected($this->cursor);
        }

        /**
         * Method to get the database collation in use by sampling a text field of a table in the database.
         *
         * @return  mixed  The collation in use by the database or boolean false if not supported.
         *
         * @since   12.1
         */
        public function getCollation()
        {
                // TODO: Not fake this
                return 'MSSQL UTF-8 (UCS2)';
        }

        /**
         * Get the number of returned rows for the previous executed SQL statement.
         *
         * @param   resource  $cursor  An optional database cursor resource to extract the row count from.
         *
         * @return  integer   The number of returned rows.
         *
         * @since   12.1
         */
        public function getNumRows($cursor = null)
        {
                $this->connect();

                return sqlsrv_num_rows($cursor ? $cursor : $this->cursor);
        }

        /**
         * Retrieves field information about the given tables.
         *
         * @param   mixed    $table     A table name
         * @param   boolean  $typeOnly  True to only return field types.
         *
         * @return  array  An array of fields.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function getTableColumns($table, $typeOnly = true)
        {
                $result = array();

                $table_temp = $this->replacePrefix((string) $table);

                // Set the query to get the table fields statement.
                $this->setQuery(
                        'SELECT column_name as Field, data_type as Type, is_nullable as \'Null\', column_default as \'Default\'' .
                        ' FROM information_schema.columns WHERE table_name = ' . $this->quote($table_temp)
                );
                $fields = $this->loadObjectList();

                // If we only want the type as the value add just that to the list.
                if ($typeOnly)
                {
                        foreach ($fields as $field)
                        {
                                $result[$field->Field] = preg_replace("/[(0-9)]/", '', $field->Type);
                        }
                }
                // If we want the whole field data object add that to the list.
                else
                {
                        foreach ($fields as $field)
                        {
                                $result[$field->Field] = $field;
                        }
                }

                return $result;
        }

        /**
         * Shows the table CREATE statement that creates the given tables.
         *
         * This is unsupported by MSSQL.
         *
         * @param   mixed  $tables  A table name or a list of table names.
         *
         * @return  array  A list of the create SQL for the tables.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function getTableCreate($tables)
        {
                $this->connect();

                return '';
        }

        /**
         * Get the details list of keys for a table.
         *
         * @param   string  $table  The name of the table.
         *
         * @return  array  An array of the column specification for the table.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function getTableKeys($table)
        {
                $this->connect();

                // TODO To implement.
                return array();
        }

        /**
         * Method to get an array of all tables in the database.
         *
         * @return  array  An array of all the tables in the database.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function getTableList()
        {
                $this->connect();

                // Set the query to get the tables statement.
                $this->setQuery('SELECT name FROM ' . $this->getDatabase() . '.sys.Tables WHERE type = \'U\';');
                $tables = $this->loadColumn();

                return $tables;
        }

        /**
         * Get the version of the database connector.
         *
         * @return  string  The database connector version.
         *
         * @since   12.1
         */
        public function getVersion()
        {
                $this->connect();

                $version = sqlsrv_server_info($this->connection);

                return $version['SQLServerVersion'];
        }

        /**
         * Inserts a row into a table based on an object's properties.
         *
         * @param   string  $table    The name of the database table to insert into.
         * @param   object  &$object  A reference to an object whose public properties match the table fields.
         * @param   string  $key      The name of the primary key. If provided the object property is updated.
         *
         * @return  boolean    True on success.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function insertObject($table, &$object, $key = null)
        {
                $fields = array();
                $values = array();
                $statement = 'INSERT INTO ' . $this->quoteName($table) . ' (%s) VALUES (%s)';

                foreach (get_object_vars($object) as $k => $v)
                {
                        // Only process non-null scalars.
                        if (is_array($v) or is_object($v) or $v === null)
                        {
                                continue;
                        }

                        if (!$this->checkFieldExists($table, $k))
                        {
                                continue;
                        }

                        if ($k[0] == '_')
                        {
                                // Internal field
                                continue;
                        }

                        if ($k == $key && $key == 0)
                        {
                                continue;
                        }

                        $fields[] = $this->quoteName($k);
                        $values[] = $this->Quote($v);
                }
                // Set the query and execute the insert.
                $this->setQuery(sprintf($statement, implode(',', $fields), implode(',', $values)));

                if (!$this->execute())
                {
                        return false;
                }

                $id = $this->insertid();

                if ($key && $id)
                {
                        $object->$key = $id;
                }

                return true;
        }

        /**
         * Method to get the auto-incremented value from the last INSERT statement.
         *
         * @return  integer  The value of the auto-increment field from the last inserted row.
         *
         * @since   12.1
         */
        public function insertid()
        {
                $this->connect();

                // TODO: SELECT IDENTITY
                $this->setQuery('SELECT @@IDENTITY');

                return (int) $this->loadResult();
        }

        /**
         * Method to get the first field of the first row of the result set from the database query.
         *
         * @return  mixed  The return value or null if the query failed.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function loadResult()
        {
                $ret = null;

                // Execute the query and get the result set cursor.
                if (!($cursor = $this->execute()))
                {
                        return null;
                }

                // Get the first row from the result set as an array.
                if ($row = sqlsrv_fetch_array($cursor, SQLSRV_FETCH_NUMERIC))
                {
                        $ret = $row[0];
                }

                // Free up system resources and return.
                $this->freeResult($cursor);

                // For SQLServer - we need to strip slashes
                $ret = stripslashes($ret);

                return $ret;
        }

        /**
         * Execute the SQL statement.
         *
         * @return  mixed  A database cursor resource on success, boolean false on failure.
         *
         * @since   12.1
         * @throws  RuntimeException
         * @throws  Exception
         */
        public function execute()
        {
                $this->connect();

                if (!is_resource($this->connection))
                {
                        JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'database');
                        throw new RuntimeException($this->errorMsg, $this->errorNum);
                }

                // Take a local copy so that we don't modify the original query and cause issues later
                $query = $this->replacePrefix((string) $this->sql);

                if (!($this->sql instanceof JDatabaseQuery) && ($this->limit > 0 || $this->offset > 0))
                {
                        $query = $this->limit($query, $this->limit, $this->offset);
                }

                // Increment the query counter.
                $this->count++;

                // Reset the error values.
                $this->errorNum = 0;
                $this->errorMsg = '';

                // If debugging is enabled then let's log the query.
                if ($this->debug)
                {
                        // Add the query to the object queue.
                        $this->log[] = $query;

                        JLog::add($query, JLog::DEBUG, 'databasequery');

                        $this->timings[] = microtime(true);
                }

                // SQLSrv_num_rows requires a static or keyset cursor.
                if (strncmp(ltrim(strtoupper($query)), 'SELECT', strlen('SELECT')) == 0)
                {
                        $array = array('Scrollable' => SQLSRV_CURSOR_KEYSET);
                }
                else
                {
                        $array = array();
                }

                // Execute the query. Error suppression is used here to prevent warnings/notices that the connection has been lost.
                $this->cursor = @sqlsrv_query($this->connection, $query, array(), $array);

                if ($this->debug)
                {
                        $this->timings[] = microtime(true);
                        if (defined('DEBUG_BACKTRACE_IGNORE_ARGS'))
                        {
                                $this->callStacks[] = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
                        }
                        else
                        {
                                $this->callStacks[] = debug_backtrace();
                        }
                }

                // If an error occurred handle it.
                if (!$this->cursor)
                {
                        // Check if the server was disconnected.
                        if (!$this->connected())
                        {
                                try
                                {
                                        // Attempt to reconnect.
                                        $this->connection = null;
                                        $this->connect();
                                }
                                // If connect fails, ignore that exception and throw the normal exception.
                                catch (RuntimeException $e)
                                {
                                        // Get the error number and message.
                                        $errors = sqlsrv_errors();
                                        $this->errorNum = $errors[0]['SQLSTATE'];
                                        $this->errorMsg = $errors[0]['message'] . 'SQL=' . $query;

                                        // Throw the normal query exception.
                                        JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'databasequery');
                                        throw new RuntimeException($this->errorMsg, $this->errorNum);
                                }

                                // Since we were able to reconnect, run the query again.
                                return $this->execute();
                        }
                        // The server was not disconnected.
                        else
                        {
                                // Get the error number and message.
                                $errors = sqlsrv_errors();
                                $this->errorNum = $errors[0]['SQLSTATE'];
                                $this->errorMsg = $errors[0]['message'] . 'SQL=' . $query;

                                // Throw the normal query exception.
                                JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'databasequery');
                                throw new RuntimeException($this->errorMsg, $this->errorNum);
                        }
                }

                return $this->cursor;
        }

        /**
         * This function replaces a string identifier <var>$prefix</var> with the string held is the
         * <var>tablePrefix</var> class variable.
         *
         * @param   string  $query   The SQL statement to prepare.
         * @param   string  $prefix  The common table prefix.
         *
         * @return  string  The processed SQL statement.
         *
         * @since   12.1
         */
        public function replacePrefix($query, $prefix = '#__')
        {
                $startPos = 0;
                $literal = '';

                $query = trim($query);
                $n = strlen($query);

                while ($startPos < $n)
                {
                        $ip = strpos($query, $prefix, $startPos);

                        if ($ip === false)
                        {
                                break;
                        }

                        $j = strpos($query, "N'", $startPos);
                        $k = strpos($query, '"', $startPos);

                        if (($k !== false) && (($k < $j) || ($j === false)))
                        {
                                $quoteChar = '"';
                                $j = $k;
                        }
                        else
                        {
                                $quoteChar = "'";
                        }

                        if ($j === false)
                        {
                                $j = $n;
                        }

                        $literal .= str_replace($prefix, $this->tablePrefix, substr($query, $startPos, $j - $startPos));
                        $startPos = $j;

                        $j = $startPos + 1;

                        if ($j >= $n)
                        {
                                break;
                        }

                        // Quote comes first, find end of quote
                        while (true)
                        {
                                $k = strpos($query, $quoteChar, $j);
                                $escaped = false;

                                if ($k === false)
                                {
                                        break;
                                }

                                $l = $k - 1;

                                while ($l >= 0 && $query{$l} == '\\')
                                {
                                        $l--;
                                        $escaped = !$escaped;
                                }

                                if ($escaped)
                                {
                                        $j = $k + 1;
                                        continue;
                                }

                                break;
                        }

                        if ($k === false)
                        {
                                // Error in the query - no end quote; ignore it
                                break;
                        }

                        $literal .= substr($query, $startPos, $k - $startPos + 1);
                        $startPos = $k + 1;
                }

                if ($startPos < $n)
                {
                        $literal .= substr($query, $startPos, $n - $startPos);
                }

                return $literal;
        }

        /**
         * Select a database for use.
         *
         * @param   string  $database  The name of the database to select for use.
         *
         * @return  boolean  True if the database was successfully selected.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function select($database)
        {
                $this->connect();

                if (!$database)
                {
                        return false;
                }

                if (!sqlsrv_query($this->connection, 'USE ' . $database, null, array('scrollable' => SQLSRV_CURSOR_STATIC)))
                {
                        throw new RuntimeException('Could not connect to database');
                }

                return true;
        }

        /**
         * Set the connection to use UTF-8 character encoding.
         *
         * @return  boolean  True on success.
         *
         * @since   12.1
         */
        public function setUTF()
        {
                // TODO: Remove this?
        }

        /**
         * Method to commit a transaction.
         *
         * @param   boolean  $toSavepoint  If true, commit to the last savepoint.
         *
         * @return  void
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function transactionCommit($toSavepoint = false)
        {
                $this->connect();

                if (!$toSavepoint || $this->transactionDepth <= 1)
                {
                        if ($this->setQuery('COMMIT TRANSACTION')->execute())
                        {
                                $this->transactionDepth = 0;
                        }

                        return;
                }

                $this->transactionDepth--;
        }

        /**
         * Method to roll back a transaction.
         *
         * @param   boolean  $toSavepoint  If true, rollback to the last savepoint.
         *
         * @return  void
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function transactionRollback($toSavepoint = false)
        {
                $this->connect();

                if (!$toSavepoint || $this->transactionDepth <= 1)
                {
                        if ($this->setQuery('ROLLBACK TRANSACTION')->execute())
                        {
                                $this->transactionDepth = 0;
                        }

                        return;
                }

                $savepoint = 'SP_' . ($this->transactionDepth - 1);
                $this->setQuery('ROLLBACK TRANSACTION ' . $this->quoteName($savepoint));

                if ($this->execute())
                {
                        $this->transactionDepth--;
                }
        }

        /**
         * Method to initialize a transaction.
         *
         * @param   boolean  $asSavepoint  If true and a transaction is already active, a savepoint will be created.
         *
         * @return  void
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function transactionStart($asSavepoint = false)
        {
                $this->connect();

                if (!$asSavepoint || !$this->transactionDepth)
                {
                        if ($this->setQuery('BEGIN TRANSACTION')->execute())
                        {
                                $this->transactionDepth = 1;
                        }

                        return;
                }

                $savepoint = 'SP_' . $this->transactionDepth;
                $this->setQuery('BEGIN TRANSACTION ' . $this->quoteName($savepoint));

                if ($this->execute())
                {
                        $this->transactionDepth++;
                }
        }

        /**
         * Method to fetch a row from the result set cursor as an array.
         *
         * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
         *
         * @return  mixed  Either the next row from the result set or false if there are no more rows.
         *
         * @since   12.1
         */
        protected function fetchArray($cursor = null)
        {
                return sqlsrv_fetch_array($cursor ? $cursor : $this->cursor, SQLSRV_FETCH_NUMERIC);
        }

        /**
         * Method to fetch a row from the result set cursor as an associative array.
         *
         * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
         *
         * @return  mixed  Either the next row from the result set or false if there are no more rows.
         *
         * @since   12.1
         */
        protected function fetchAssoc($cursor = null)
        {
                return sqlsrv_fetch_array($cursor ? $cursor : $this->cursor, SQLSRV_FETCH_ASSOC);
        }

        /**
         * Method to fetch a row from the result set cursor as an object.
         *
         * @param   mixed   $cursor  The optional result set cursor from which to fetch the row.
         * @param   string  $class   The class name to use for the returned row object.
         *
         * @return  mixed   Either the next row from the result set or false if there are no more rows.
         *
         * @since   12.1
         */
        protected function fetchObject($cursor = null, $class = 'stdClass')
        {
                return sqlsrv_fetch_object($cursor ? $cursor : $this->cursor, $class);
        }

        /**
         * Method to free up the memory used for the result set.
         *
         * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
         *
         * @return  void
         *
         * @since   12.1
         */
        protected function freeResult($cursor = null)
        {
                sqlsrv_free_stmt($cursor ? $cursor : $this->cursor);
        }

        /**
         * Method to check and see if a field exists in a table.
         *
         * @param   string  $table  The table in which to verify the field.
         * @param   string  $field  The field to verify.
         *
         * @return  boolean  True if the field exists in the table.
         *
         * @since   12.1
         */
        protected function checkFieldExists($table, $field)
        {
                $this->connect();

                $table = $this->replacePrefix((string) $table);
                $query = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" .
                        " ORDER BY ORDINAL_POSITION";
                $this->setQuery($query);

                if ($this->loadResult())
                {
                        return true;
                }
                else
                {
                        return false;
                }
        }

        /**
         * Method to wrap an SQL statement to provide a LIMIT and OFFSET behavior for scrolling through a result set.
         *
         * @param   string   $query   The SQL statement to process.
         * @param   integer  $limit   The maximum affected rows to set.
         * @param   integer  $offset  The affected row offset to set.
         *
         * @return  string   The processed SQL statement.
         *
         * @since   12.1
         */
        protected function limit($query, $limit, $offset)
        {
                if ($limit == 0 && $offset == 0)
                {
                        return $query;
                }

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

                $orderBy = stristr($query, 'ORDER BY');

                if (is_null($orderBy) || empty($orderBy))
                {
                        $orderBy = 'ORDER BY (select 0)';
                }

                $query = str_ireplace($orderBy, '', $query);

                $rowNumberText = ', ROW_NUMBER() OVER (' . $orderBy . ') AS RowNumber FROM ';

                $query = preg_replace('/\sFROM\s/i', $rowNumberText, $query, 1);
                $query = 'SELECT * FROM (' . $query . ') _myResults WHERE RowNumber BETWEEN ' . $start . ' AND ' . $end;

                return $query;
        }

        /**
         * Renames a table in the database.
         *
         * @param   string  $oldTable  The name of the table to be renamed
         * @param   string  $newTable  The new name for the table.
         * @param   string  $backup    Table prefix
         * @param   string  $prefix    For the table - used to rename constraints in non-mysql databases
         *
         * @return  JDatabaseDriverSqlsrv  Returns this object to support chaining.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function renameTable($oldTable, $newTable, $backup = null, $prefix = null)
        {
                $constraints = array();

                if (!is_null($prefix) && !is_null($backup))
                {
                        $constraints = $this->getTableConstraints($oldTable);
                }
                if (!empty($constraints))
                {
                        $this->renameConstraints($constraints, $prefix, $backup);
                }

                $this->setQuery("sp_rename '" . $oldTable . "', '" . $newTable . "'");

                return $this->execute();
        }

        /**
         * Locks a table in the database.
         *
         * @param   string  $tableName  The name of the table to lock.
         *
         * @return  JDatabaseDriverSqlsrv  Returns this object to support chaining.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function lockTable($tableName)
        {
                return $this;
        }

        /**
         * Unlocks tables in the database.
         *
         * @return  JDatabaseDriverSqlsrv  Returns this object to support chaining.
         *
         * @since   12.1
         * @throws  RuntimeException
         */
        public function unlockTables()
        {
                return $this;
        }
}