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<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package             CodeIgniter
 * @author              ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license             http://codeigniter.com/user_guide/license.html
 * @link                http://codeigniter.com
 * @since               Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------

/**
 * SQLSRV Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the active record
 * class is being used or not.
 *
 * @package             CodeIgniter
 * @subpackage  Drivers
 * @category    Database
 * @author              ExpressionEngine Dev Team
 * @link                http://codeigniter.com/user_guide/database/
 */
class CI_DB_sqlsrv_driver extends CI_DB {

        var $dbdriver = 'sqlsrv';

        // The character used for escaping
        var $_escape_char = '';

        // clause and character used for LIKE escape sequences
        var $_like_escape_str = " ESCAPE '%s' ";
        var $_like_escape_chr = '!';

        /**
         * The syntax to count rows is slightly different across different
         * database engines, so this string appears in each driver and is
         * used for the count_all() and count_all_results() functions.
         */
        var $_count_string = "SELECT COUNT(*) AS ";
        var $_random_keyword = ' ASC'; // not currently supported

        /**
         * Non-persistent database connection
         *
         * @access      private called by the base class
         * @return      resource
         */
        function db_connect($pooling = false)
        {
                // Check for a UTF-8 charset being passed as CI's default 'utf8'.
                $character_set = (0 === strcasecmp('utf8', $this->char_set)) ? 'UTF-8' : $this->char_set;

                $connection = array(
                        'UID'                           => empty($this->username) ? '' : $this->username,
                        'PWD'                           => empty($this->password) ? '' : $this->password,
                        'Database'                      => $this->database,
                        'ConnectionPooling' => $pooling ? 1 : 0,
                        'CharacterSet'          => $character_set,
                        'ReturnDatesAsStrings' => 1
                );
                
                // If the username and password are both empty, assume this is a 
                // 'Windows Authentication Mode' connection.
                if(empty($connection['UID']) && empty($connection['PWD'])) {
                        unset($connection['UID'], $connection['PWD']);
                }

                return sqlsrv_connect($this->hostname, $connection);
        }

        // --------------------------------------------------------------------

        /**
         * Persistent database connection
         *
         * @access      private called by the base class
         * @return      resource
         */
        function db_pconnect()
        {
                $this->db_connect(TRUE);
        }

        // --------------------------------------------------------------------

        /**
         * Reconnect
         *
         * Keep / reestablish the db connection if no queries have been
         * sent for a length of time exceeding the server's idle timeout
         *
         * @access      public
         * @return      void
         */
        function reconnect()
        {
                // not implemented in MSSQL
        }

        // --------------------------------------------------------------------

        /**
         * Select the database
         *
         * @access      private called by the base class
         * @return      resource
         */
        function db_select()
        {
                return $this->_execute('USE ' . $this->database);
        }

        // --------------------------------------------------------------------

        /**
         * Set client character set
         *
         * @access      public
         * @param       string
         * @param       string
         * @return      resource
         */
        function db_set_charset($charset, $collation)
        {
                // @todo - add support if needed
                return TRUE;
        }

        // --------------------------------------------------------------------

        /**
         * Execute the query
         *
         * @access      private called by the base class
         * @param       string  an SQL query
         * @return      resource
         */
        function _execute($sql)
        {
                $sql = $this->_prep_query($sql);
                return sqlsrv_query($this->conn_id, $sql, null, array(
                        'Scrollable'                            => SQLSRV_CURSOR_STATIC,
                        'SendStreamParamsAtExec'        => true
                ));
        }

        // --------------------------------------------------------------------

        /**
         * Prep the query
         *
         * If needed, each database adapter can prep the query string
         *
         * @access      private called by execute()
         * @param       string  an SQL query
         * @return      string
         */
        function _prep_query($sql)
        {
                return $sql;
        }

        // --------------------------------------------------------------------

        /**
         * Begin Transaction
         *
         * @access      public
         * @return      bool
         */
        function trans_begin($test_mode = FALSE)
        {
                if ( ! $this->trans_enabled)
                {
                        return TRUE;
                }

                // When transactions are nested we only begin/commit/rollback the outermost ones
                if ($this->_trans_depth > 0)
                {
                        return TRUE;
                }

                // Reset the transaction failure flag.
                // If the $test_mode flag is set to TRUE transactions will be rolled back
                // even if the queries produce a successful result.
                $this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;

                return sqlsrv_begin_transaction($this->conn_id);
        }

        // --------------------------------------------------------------------

        /**
         * Commit Transaction
         *
         * @access      public
         * @return      bool
         */
        function trans_commit()
        {
                if ( ! $this->trans_enabled)
                {
                        return TRUE;
                }

                // When transactions are nested we only begin/commit/rollback the outermost ones
                if ($this->_trans_depth > 0)
                {
                        return TRUE;
                }

                return sqlsrv_commit($this->conn_id);
        }

        // --------------------------------------------------------------------

        /**
         * Rollback Transaction
         *
         * @access      public
         * @return      bool
         */
        function trans_rollback()
        {
                if ( ! $this->trans_enabled)
                {
                        return TRUE;
                }

                // When transactions are nested we only begin/commit/rollback the outermost ones
                if ($this->_trans_depth > 0)
                {
                        return TRUE;
                }

                return sqlsrv_rollback($this->conn_id);
        }

        // --------------------------------------------------------------------

        /**
         * Escape String
         *
         * @access      public
         * @param       string
         * @param       bool    whether or not the string will be used in a LIKE condition
         * @return      string
         */
        function escape_str($str, $like = FALSE)
        {
                // Escape single quotes
                return str_replace("'", "''", $str);
        }

        // --------------------------------------------------------------------

        /**
         * Affected Rows
         *
         * @access      public
         * @return      integer
         */
        function affected_rows()
        {
                return @sqlrv_rows_affected($this->conn_id);
        }

        // --------------------------------------------------------------------

        /**
        * Insert ID
        *
        * Returns the last id created in the Identity column.
        *
        * @access public
        * @return integer
        */
        function insert_id()
        {
                return $this->query('select @@IDENTITY as insert_id')->row('insert_id');
        }

        // --------------------------------------------------------------------

        /**
        * Parse major version
        *
        * Grabs the major version number from the
        * database server version string passed in.
        *
        * @access private
        * @param string $version
        * @return int16 major version number
        */
        function _parse_major_version($version)
        {
                preg_match('/([0-9]+)\.([0-9]+)\.([0-9]+)/', $version, $ver_info);
                return $ver_info[1]; // return the major version b/c that's all we're interested in.
        }

        // --------------------------------------------------------------------

        /**
        * Version number query string
        *
        * @access public
        * @return string
        */
        function _version()
        {
                $info = sqlsrv_server_info($this->conn_id);
                return sprintf("select '%s' as ver", $info['SQLServerVersion']);
        }

        // --------------------------------------------------------------------

        /**
         * "Count All" query
         *
         * Generates a platform-specific query string that counts all records in
         * the specified database
         *
         * @access      public
         * @param       string
         * @return      string
         */
        function count_all($table = '')
        {
                if ($table == '')
                        return '0';
        
                $query = $this->query("SELECT COUNT(*) AS numrows FROM " . $this->dbprefix . $table);
                
                if ($query->num_rows() == 0)
                        return '0';

                $row = $query->row();
                $this->_reset_select();
                return $row->numrows;
        }

        // --------------------------------------------------------------------

        /**
         * List table query
         *
         * Generates a platform-specific query string so that the table names can be fetched
         *
         * @access      private
         * @param       boolean
         * @return      string
         */
        function _list_tables($prefix_limit = FALSE)
        {
                return "SELECT name FROM sysobjects WHERE type = 'U' ORDER BY name";
        }

        // --------------------------------------------------------------------

        /**
         * List column query
         *
         * Generates a platform-specific query string so that the column names can be fetched
         *
         * @access      private
         * @param       string  the table name
         * @return      string
         */
        function _list_columns($table = '')
        {
                return "SELECT * FROM INFORMATION_SCHEMA.Columns WHERE TABLE_NAME = '".$this->_escape_table($table)."'";
        }

        // --------------------------------------------------------------------

        /**
         * Field data query
         *
         * Generates a platform-specific query so that the column data can be retrieved
         *
         * @access      public
         * @param       string  the table name
         * @return      object
         */
        function _field_data($table)
        {
                return "SELECT TOP 1 * FROM " . $this->_escape_table($table);   
        }

        // --------------------------------------------------------------------

        /**
         * The error message string
         *
         * @access      private
         * @return      string
         */
        function _error_message()
        {
                $error = array_shift(sqlsrv_errors());
                return !empty($error['message']) ? $error['message'] : null;
        }

        // --------------------------------------------------------------------

        /**
         * The error message number
         *
         * @access      private
         * @return      integer
         */
        function _error_number()
        {
                $error = array_shift(sqlsrv_errors());
                return isset($error['SQLSTATE']) ? $error['SQLSTATE'] : null;
        }

        // --------------------------------------------------------------------

        /**
         * Escape Table Name
         *
         * This function adds backticks if the table name has a period
         * in it. Some DBs will get cranky unless periods are escaped
         *
         * @access      private
         * @param       string  the table name
         * @return      string
         */
        function _escape_table($table)
        {
                return $table;
        }       


        /**
         * Escape the SQL Identifiers
         *
         * This function escapes column and table names
         *
         * @access      private
         * @param       string
         * @return      string
         */
        function _escape_identifiers($item)
        {
                return $item;
        }

        // --------------------------------------------------------------------

        /**
         * From Tables
         *
         * This function implicitly groups FROM tables so there is no confusion
         * about operator precedence in harmony with SQL standards
         *
         * @access      public
         * @param       type
         * @return      type
         */
        function _from_tables($tables)
        {
                if ( ! is_array($tables))
                {
                        $tables = array($tables);
                }

                return implode(', ', $tables);
        }

        // --------------------------------------------------------------------

        /**
         * Insert statement
         *
         * Generates a platform-specific insert string from the supplied data
         *
         * @access      public
         * @param       string  the table name
         * @param       array   the insert keys
         * @param       array   the insert values
         * @return      string
         */
        function _insert($table, $keys, $values)
        {       
                return "INSERT INTO ".$this->_escape_table($table)." (".implode(', ', $keys).") VALUES (".implode(', ', $values).")";
        }

        // --------------------------------------------------------------------

        /**
         * Update statement
         *
         * Generates a platform-specific update string from the supplied data
         *
         * @access      public
         * @param       string  the table name
         * @param       array   the update data
         * @param       array   the where clause
         * @param       array   the orderby clause
         * @param       array   the limit clause
         * @return      string
         */
        function _update($table, $values, $where)
        {
                foreach($values as $key => $val)
                {
                        $valstr[] = $key." = ".$val;
                }
        
                return "UPDATE ".$this->_escape_table($table)." SET ".implode(', ', $valstr)." WHERE ".implode(" ", $where);
        }
        
        // --------------------------------------------------------------------

        /**
         * Truncate statement
         *
         * Generates a platform-specific truncate string from the supplied data
         * If the database does not support the truncate() command
         * This function maps to "DELETE FROM table"
         *
         * @access      public
         * @param       string  the table name
         * @return      string
         */
        function _truncate($table)
        {
                return "TRUNCATE ".$table;
        }

        // --------------------------------------------------------------------

        /**
         * Delete statement
         *
         * Generates a platform-specific delete string from the supplied data
         *
         * @access      public
         * @param       string  the table name
         * @param       array   the where clause
         * @param       string  the limit clause
         * @return      string
         */
        function _delete($table, $where)
        {
                return "DELETE FROM ".$this->_escape_table($table)." WHERE ".implode(" ", $where);
        }

        // --------------------------------------------------------------------

        /**
         * Limit string
         *
         * Generates a platform-specific LIMIT clause
         *
         * @access      public
         * @param       string  the sql query string
         * @param       integer the number of rows to limit the query to
         * @param       integer the offset value
         * @return      string
         */
        function _limit($sql, $limit, $offset)
        {
                $i = $limit + $offset;
        
                return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$i.' ', $sql);               
        }

        // --------------------------------------------------------------------

        /**
         * Close DB Connection
         *
         * @access      public
         * @param       resource
         * @return      void
         */
        function _close($conn_id)
        {
                @sqlsrv_close($conn_id);
        }

}



/* End of file mssql_driver.php */
/* Location: ./system/database/drivers/mssql/mssql_driver.php */