1 <?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
5 * An open source application development framework for PHP 5.1.6 or newer
8 * @author ExpressionEngine Dev Team
9 * @copyright Copyright (c) 2008 - 2011, EllisLab, Inc.
10 * @license http://codeigniter.com/user_guide/license.html
11 * @link http://codeigniter.com
16 // ------------------------------------------------------------------------
19 * Database Driver Class
21 * This is the platform-independent base DB implementation class.
22 * This class will not be called directly. Rather, the adapter
23 * class for the specific database will extend and instantiate it.
25 * @package CodeIgniter
28 * @author ExpressionEngine Dev Team
29 * @link http://codeigniter.com/user_guide/database/
37 var $dbdriver = 'mysql';
39 var $char_set = 'utf8';
40 var $dbcollat = 'utf8_general_ci';
41 var $autoinit = TRUE; // Whether to automatically initialize the DB
44 var $pconnect = FALSE;
46 var $result_id = FALSE;
47 var $db_debug = FALSE;
50 var $bind_marker = '?';
51 var $save_queries = TRUE;
52 var $queries = array();
53 var $query_times = array();
54 var $data_cache = array();
55 var $trans_enabled = TRUE;
56 var $trans_strict = TRUE;
57 var $_trans_depth = 0;
58 var $_trans_status = TRUE; // Used with transactions to determine if a rollback should occur
59 var $cache_on = FALSE;
61 var $cache_autodel = FALSE;
62 var $CACHE; // The cache class object
65 var $_protect_identifiers = TRUE;
66 var $_reserved_identifiers = array('*'); // Identifiers that should NOT be escaped
68 // These are use with Oracle
76 * Constructor. Accepts one parameter containing the database
77 * connection settings.
81 function CI_DB_driver($params)
83 if (is_array($params))
85 foreach ($params as $key => $val)
91 log_message('debug', 'Database Driver Class Initialized');
94 // --------------------------------------------------------------------
97 * Initialize Database Settings
99 * @access private Called by the constructor
103 function initialize()
105 // If an existing connection resource is available
106 // there is no need to connect and select the database
107 if (is_resource($this->conn_id) OR is_object($this->conn_id))
112 // ----------------------------------------------------------------
114 // Connect to the database and set the connection ID
115 $this->conn_id = ($this->pconnect == FALSE) ? $this->db_connect() : $this->db_pconnect();
117 // No connection resource? Throw an error
118 if ( ! $this->conn_id)
120 log_message('error', 'Unable to connect to the database');
124 $this->display_error('db_unable_to_connect');
129 // ----------------------------------------------------------------
131 // Select the DB... assuming a database name is specified in the config file
132 if ($this->database != '')
134 if ( ! $this->db_select())
136 log_message('error', 'Unable to select database: '.$this->database);
140 $this->display_error('db_unable_to_select', $this->database);
146 // We've selected the DB. Now we set the character set
147 if ( ! $this->db_set_charset($this->char_set, $this->dbcollat))
159 // --------------------------------------------------------------------
162 * Set client character set
169 function db_set_charset($charset, $collation)
171 if ( ! $this->_db_set_charset($this->char_set, $this->dbcollat))
173 log_message('error', 'Unable to set database connection charset: '.$this->char_set);
177 $this->display_error('db_unable_to_set_charset', $this->char_set);
186 // --------------------------------------------------------------------
189 * The name of the platform in use (mysql, mssql, etc...)
196 return $this->dbdriver;
199 // --------------------------------------------------------------------
202 * Database Version Number. Returns a string containing the
203 * version of the database being used
210 if (FALSE === ($sql = $this->_version()))
214 return $this->display_error('db_unsupported_function');
219 // Some DBs have functions that return the version, and don't run special
220 // SQL queries per se. In these instances, just return the result.
221 $driver_version_exceptions = array('oci8', 'sqlite');
223 if (in_array($this->dbdriver, $driver_version_exceptions))
229 $query = $this->query($sql);
230 return $query->row('ver');
234 // --------------------------------------------------------------------
239 * Accepts an SQL string as input and returns a result object upon
240 * successful execution of a "read" type query. Returns boolean TRUE
241 * upon successful execution of a "write" type query. Returns boolean
242 * FALSE upon failure, and if the $db_debug variable is set to TRUE
243 * will raise an error.
246 * @param string An SQL query string
247 * @param array An array of binding data
250 function query($sql, $binds = FALSE, $return_object = TRUE)
256 log_message('error', 'Invalid query: '.$sql);
257 return $this->display_error('db_invalid_query');
262 // Verify table prefix and replace if necessary
263 if ( ($this->dbprefix != '' AND $this->swap_pre != '') AND ($this->dbprefix != $this->swap_pre) )
265 $sql = preg_replace("/(\W)".$this->swap_pre."(\S+?)/", "\\1".$this->dbprefix."\\2", $sql);
268 // Is query caching enabled? If the query is a "read type"
269 // we will load the caching class and return the previously
270 // cached query if it exists
271 if ($this->cache_on == TRUE AND stristr($sql, 'SELECT'))
273 if ($this->_cache_init())
275 $this->load_rdriver();
276 if (FALSE !== ($cache = $this->CACHE->read($sql)))
283 // Compile binds if needed
284 if ($binds !== FALSE)
286 $sql = $this->compile_binds($sql, $binds);
289 // Save the query for debugging
290 if ($this->save_queries == TRUE)
292 $this->queries[] = $sql;
295 // Start the Query Timer
296 $time_start = list($sm, $ss) = explode(' ', microtime());
299 if (FALSE === ($this->result_id = $this->simple_query($sql)))
301 if ($this->save_queries == TRUE)
303 $this->query_times[] = 0;
306 // This will trigger a rollback if transactions are being used
307 $this->_trans_status = FALSE;
311 // grab the error number and message now, as we might run some
312 // additional queries before displaying the error
313 $error_no = $this->_error_number();
314 $error_msg = $this->_error_message();
316 // We call this function in order to roll-back queries
317 // if transactions are enabled. If we don't call this here
318 // the error message will trigger an exit, causing the
319 // transactions to remain in limbo.
320 $this->trans_complete();
322 // Log and display errors
323 log_message('error', 'Query error: '.$error_msg);
324 return $this->display_error(
326 'Error Number: '.$error_no,
336 // Stop and aggregate the query time results
337 $time_end = list($em, $es) = explode(' ', microtime());
338 $this->benchmark += ($em + $es) - ($sm + $ss);
340 if ($this->save_queries == TRUE)
342 $this->query_times[] = ($em + $es) - ($sm + $ss);
345 // Increment the query counter
346 $this->query_count++;
348 // Was the query a "write" type?
349 // If so we'll simply return true
350 if ($this->is_write_type($sql) === TRUE)
352 // If caching is enabled we'll auto-cleanup any
353 // existing files related to this particular URI
354 if ($this->cache_on == TRUE AND $this->cache_autodel == TRUE AND $this->_cache_init())
356 $this->CACHE->delete();
362 // Return TRUE if we don't need to create a result object
363 // Currently only the Oracle driver uses this when stored
364 // procedures are used
365 if ($return_object !== TRUE)
370 // Load and instantiate the result driver
372 $driver = $this->load_rdriver();
373 $RES = new $driver();
374 $RES->conn_id = $this->conn_id;
375 $RES->result_id = $this->result_id;
377 if ($this->dbdriver == 'oci8')
379 $RES->stmt_id = $this->stmt_id;
380 $RES->curs_id = NULL;
381 $RES->limit_used = $this->limit_used;
382 $this->stmt_id = FALSE;
385 // oci8 vars must be set before calling this
386 $RES->num_rows = $RES->num_rows();
388 // Is query caching enabled? If so, we'll serialize the
389 // result object and save it to a cache file.
390 if ($this->cache_on == TRUE AND $this->_cache_init())
392 // We'll create a new instance of the result object
393 // only without the platform specific driver since
394 // we can't use it with cached data (the query result
395 // resource ID won't be any good once we've cached the
396 // result object, so we'll have to compile the data
398 $CR = new CI_DB_result();
399 $CR->num_rows = $RES->num_rows();
400 $CR->result_object = $RES->result_object();
401 $CR->result_array = $RES->result_array();
403 // Reset these since cached objects can not utilize resource IDs.
405 $CR->result_id = NULL;
407 $this->CACHE->write($sql, $CR);
413 // --------------------------------------------------------------------
416 * Load the result drivers
419 * @return string the name of the result class
421 function load_rdriver()
423 $driver = 'CI_DB_'.$this->dbdriver.'_result';
425 if ( ! class_exists($driver))
427 include_once(BASEPATH.'database/DB_result'.EXT);
428 include_once(BASEPATH.'database/drivers/'.$this->dbdriver.'/'.$this->dbdriver.'_result'.EXT);
434 // --------------------------------------------------------------------
438 * This is a simplified version of the query() function. Internally
439 * we only use it when running transaction commands since they do
440 * not require all the features of the main query() function.
443 * @param string the sql query
446 function simple_query($sql)
448 if ( ! $this->conn_id)
453 return $this->_execute($sql);
456 // --------------------------------------------------------------------
459 * Disable Transactions
460 * This permits transactions to be disabled at run-time.
467 $this->trans_enabled = FALSE;
470 // --------------------------------------------------------------------
473 * Enable/disable Transaction Strict Mode
474 * When strict mode is enabled, if you are running multiple groups of
475 * transactions, if one group fails all groups will be rolled back.
476 * If strict mode is disabled, each group is treated autonomously, meaning
477 * a failure of one group will not affect any others
482 function trans_strict($mode = TRUE)
484 $this->trans_strict = is_bool($mode) ? $mode : TRUE;
487 // --------------------------------------------------------------------
495 function trans_start($test_mode = FALSE)
497 if ( ! $this->trans_enabled)
502 // When transactions are nested we only begin/commit/rollback the outermost ones
503 if ($this->_trans_depth > 0)
505 $this->_trans_depth += 1;
509 $this->trans_begin($test_mode);
512 // --------------------------------------------------------------------
515 * Complete Transaction
520 function trans_complete()
522 if ( ! $this->trans_enabled)
527 // When transactions are nested we only begin/commit/rollback the outermost ones
528 if ($this->_trans_depth > 1)
530 $this->_trans_depth -= 1;
534 // The query() function will set this flag to FALSE in the event that a query failed
535 if ($this->_trans_status === FALSE)
537 $this->trans_rollback();
539 // If we are NOT running in strict mode, we will reset
540 // the _trans_status flag so that subsequent groups of transactions
541 // will be permitted.
542 if ($this->trans_strict === FALSE)
544 $this->_trans_status = TRUE;
547 log_message('debug', 'DB Transaction Failure');
551 $this->trans_commit();
555 // --------------------------------------------------------------------
558 * Lets you retrieve the transaction flag to determine if it has failed
563 function trans_status()
565 return $this->_trans_status;
568 // --------------------------------------------------------------------
574 * @param string the sql statement
575 * @param array an array of bind data
578 function compile_binds($sql, $binds)
580 if (strpos($sql, $this->bind_marker) === FALSE)
585 if ( ! is_array($binds))
587 $binds = array($binds);
590 // Get the sql segments around the bind markers
591 $segments = explode($this->bind_marker, $sql);
593 // The count of bind should be 1 less then the count of segments
594 // If there are more bind arguments trim it down
595 if (count($binds) >= count($segments)) {
596 $binds = array_slice($binds, 0, count($segments)-1);
599 // Construct the binded query
600 $result = $segments[0];
602 foreach ($binds as $bind)
604 $result .= $this->escape($bind);
605 $result .= $segments[++$i];
611 // --------------------------------------------------------------------
614 * Determines if a query is a "write" type.
617 * @param string An SQL query string
620 function is_write_type($sql)
622 if ( ! preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD DATA|COPY|ALTER|GRANT|REVOKE|LOCK|UNLOCK)\s+/i', $sql))
629 // --------------------------------------------------------------------
632 * Calculate the aggregate query elapsed time
635 * @param integer The number of decimal places
638 function elapsed_time($decimals = 6)
640 return number_format($this->benchmark, $decimals);
643 // --------------------------------------------------------------------
646 * Returns the total number of queries
651 function total_queries()
653 return $this->query_count;
656 // --------------------------------------------------------------------
659 * Returns the last query that was executed
664 function last_query()
666 return end($this->queries);
669 // --------------------------------------------------------------------
672 * "Smart" Escape String
674 * Escapes data based on type
675 * Sets boolean and null types
681 function escape($str)
685 $str = "'".$this->escape_str($str)."'";
687 elseif (is_bool($str))
689 $str = ($str === FALSE) ? 0 : 1;
691 elseif (is_null($str))
699 // --------------------------------------------------------------------
704 * Calls the individual driver for platform
705 * specific escaping for LIKE conditions
711 function escape_like_str($str)
713 return $this->escape_str($str, TRUE);
716 // --------------------------------------------------------------------
721 * Retrieves the primary key. It assumes that the row in the first
722 * position is the primary key
725 * @param string the table name
728 function primary($table = '')
730 $fields = $this->list_fields($table);
732 if ( ! is_array($fields))
737 return current($fields);
740 // --------------------------------------------------------------------
743 * Returns an array of table names
748 function list_tables($constrain_by_prefix = FALSE)
750 // Is there a cached result?
751 if (isset($this->data_cache['table_names']))
753 return $this->data_cache['table_names'];
756 if (FALSE === ($sql = $this->_list_tables($constrain_by_prefix)))
760 return $this->display_error('db_unsupported_function');
766 $query = $this->query($sql);
768 if ($query->num_rows() > 0)
770 foreach ($query->result_array() as $row)
772 if (isset($row['TABLE_NAME']))
774 $retval[] = $row['TABLE_NAME'];
778 $retval[] = array_shift($row);
783 $this->data_cache['table_names'] = $retval;
784 return $this->data_cache['table_names'];
787 // --------------------------------------------------------------------
790 * Determine if a particular table exists
794 function table_exists($table_name)
796 return ( ! in_array($this->_protect_identifiers($table_name, TRUE, FALSE, FALSE), $this->list_tables())) ? FALSE : TRUE;
799 // --------------------------------------------------------------------
802 * Fetch MySQL Field Names
805 * @param string the table name
808 function list_fields($table = '')
810 // Is there a cached result?
811 if (isset($this->data_cache['field_names'][$table]))
813 return $this->data_cache['field_names'][$table];
820 return $this->display_error('db_field_param_missing');
825 if (FALSE === ($sql = $this->_list_columns($table)))
829 return $this->display_error('db_unsupported_function');
834 $query = $this->query($sql);
837 foreach ($query->result_array() as $row)
839 if (isset($row['COLUMN_NAME']))
841 $retval[] = $row['COLUMN_NAME'];
845 $retval[] = current($row);
849 $this->data_cache['field_names'][$table] = $retval;
850 return $this->data_cache['field_names'][$table];
853 // --------------------------------------------------------------------
856 * Determine if a particular field exists
862 function field_exists($field_name, $table_name)
864 return ( ! in_array($field_name, $this->list_fields($table_name))) ? FALSE : TRUE;
867 // --------------------------------------------------------------------
870 * Returns an object with field data
873 * @param string the table name
876 function field_data($table = '')
882 return $this->display_error('db_field_param_missing');
887 $query = $this->query($this->_field_data($this->_protect_identifiers($table, TRUE, NULL, FALSE)));
889 return $query->field_data();
892 // --------------------------------------------------------------------
895 * Generate an insert string
898 * @param string the table upon which the query will be performed
899 * @param array an associative array data of key/values
902 function insert_string($table, $data)
907 foreach ($data as $key => $val)
909 $fields[] = $this->_escape_identifiers($key);
910 $values[] = $this->escape($val);
913 return $this->_insert($this->_protect_identifiers($table, TRUE, NULL, FALSE), $fields, $values);
916 // --------------------------------------------------------------------
919 * Generate an update string
922 * @param string the table upon which the query will be performed
923 * @param array an associative array data of key/values
924 * @param mixed the "where" statement
927 function update_string($table, $data, $where)
935 foreach ($data as $key => $val)
937 $fields[$this->_protect_identifiers($key)] = $this->escape($val);
940 if ( ! is_array($where))
942 $dest = array($where);
947 foreach ($where as $key => $val)
949 $prefix = (count($dest) == 0) ? '' : ' AND ';
953 if ( ! $this->_has_operator($key))
958 $val = ' '.$this->escape($val);
961 $dest[] = $prefix.$key.$val;
965 return $this->_update($this->_protect_identifiers($table, TRUE, NULL, FALSE), $fields, $dest);
968 // --------------------------------------------------------------------
971 * Tests whether the string has an SQL operator
977 function _has_operator($str)
980 if ( ! preg_match("/(\s|<|>|!|=|is null|is not null)/i", $str))
988 // --------------------------------------------------------------------
991 * Enables a native PHP function to be run, using a platform agnostic wrapper.
994 * @param string the function name
995 * @param mixed any parameters needed by the function
998 function call_function($function)
1000 $driver = ($this->dbdriver == 'postgre') ? 'pg_' : $this->dbdriver.'_';
1002 if (FALSE === strpos($driver, $function))
1004 $function = $driver.$function;
1007 if ( ! function_exists($function))
1009 if ($this->db_debug)
1011 return $this->display_error('db_unsupported_function');
1017 $args = (func_num_args() > 1) ? array_splice(func_get_args(), 1) : null;
1019 return call_user_func_array($function, $args);
1023 // --------------------------------------------------------------------
1026 * Set Cache Directory Path
1029 * @param string the path to the cache directory
1032 function cache_set_path($path = '')
1034 $this->cachedir = $path;
1037 // --------------------------------------------------------------------
1040 * Enable Query Caching
1047 $this->cache_on = TRUE;
1051 // --------------------------------------------------------------------
1054 * Disable Query Caching
1059 function cache_off()
1061 $this->cache_on = FALSE;
1066 // --------------------------------------------------------------------
1069 * Delete the cache files associated with a particular URI
1074 function cache_delete($segment_one = '', $segment_two = '')
1076 if ( ! $this->_cache_init())
1080 return $this->CACHE->delete($segment_one, $segment_two);
1083 // --------------------------------------------------------------------
1086 * Delete All cache files
1091 function cache_delete_all()
1093 if ( ! $this->_cache_init())
1098 return $this->CACHE->delete_all();
1101 // --------------------------------------------------------------------
1104 * Initialize the Cache Class
1109 function _cache_init()
1111 if (is_object($this->CACHE) AND class_exists('CI_DB_Cache'))
1116 if ( ! class_exists('CI_DB_Cache'))
1118 if ( ! @include(BASEPATH.'database/DB_cache'.EXT))
1120 return $this->cache_off();
1124 $this->CACHE = new CI_DB_Cache($this); // pass db object to support multiple db connections and returned db objects
1128 // --------------------------------------------------------------------
1131 * Close DB Connection
1138 if (is_resource($this->conn_id) OR is_object($this->conn_id))
1140 $this->_close($this->conn_id);
1142 $this->conn_id = FALSE;
1145 // --------------------------------------------------------------------
1148 * Display an error message
1151 * @param string the error message
1152 * @param string any "swap" values
1153 * @param boolean whether to localize the message
1154 * @return string sends the application/error_db.php template
1156 function display_error($error = '', $swap = '', $native = FALSE)
1158 $LANG =& load_class('Lang', 'core');
1161 $heading = $LANG->line('db_error_heading');
1163 if ($native == TRUE)
1169 $message = ( ! is_array($error)) ? array(str_replace('%s', $swap, $LANG->line($error))) : $error;
1172 // Find the most likely culprit of the error by going through
1173 // the backtrace until the source file is no longer in the
1176 $trace = debug_backtrace();
1178 foreach ($trace as $call)
1180 if (isset($call['file']) && strpos($call['file'], BASEPATH.'database') === FALSE)
1182 // Found it - use a relative path for safety
1183 $message[] = 'Filename: '.str_replace(array(BASEPATH, APPPATH), '', $call['file']);
1184 $message[] = 'Line Number: '.$call['line'];
1190 $error =& load_class('Exceptions', 'core');
1191 echo $error->show_error($heading, $message, 'error_db');
1195 // --------------------------------------------------------------------
1198 * Protect Identifiers
1200 * This function adds backticks if appropriate based on db type
1203 * @param mixed the item to escape
1204 * @return mixed the item with backticks
1206 function protect_identifiers($item, $prefix_single = FALSE)
1208 return $this->_protect_identifiers($item, $prefix_single);
1211 // --------------------------------------------------------------------
1214 * Protect Identifiers
1216 * This function is used extensively by the Active Record class, and by
1217 * a couple functions in this class.
1218 * It takes a column or table name (optionally with an alias) and inserts
1219 * the table prefix onto it. Some logic is necessary in order to deal with
1220 * column names that include the path. Consider a query like this:
1222 * SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table
1224 * Or a query with aliasing:
1226 * SELECT m.member_id, m.member_name FROM members AS m
1228 * Since the column name can include up to four segments (host, DB, table, column)
1229 * or also have an alias prefix, we need to do a bit of work to figure this out and
1230 * insert the table prefix (if it exists) in the proper position, and escape only
1231 * the correct identifiers.
1240 function _protect_identifiers($item, $prefix_single = FALSE, $protect_identifiers = NULL, $field_exists = TRUE)
1242 if ( ! is_bool($protect_identifiers))
1244 $protect_identifiers = $this->_protect_identifiers;
1247 if (is_array($item))
1249 $escaped_array = array();
1251 foreach ($item as $k => $v)
1253 $escaped_array[$this->_protect_identifiers($k)] = $this->_protect_identifiers($v);
1256 return $escaped_array;
1259 // Convert tabs or multiple spaces into single spaces
1260 $item = preg_replace('/[\t ]+/', ' ', $item);
1262 // If the item has an alias declaration we remove it and set it aside.
1263 // Basically we remove everything to the right of the first space
1265 if (strpos($item, ' ') !== FALSE)
1267 $alias = strstr($item, " ");
1268 $item = substr($item, 0, - strlen($alias));
1271 // This is basically a bug fix for queries that use MAX, MIN, etc.
1272 // If a parenthesis is found we know that we do not need to
1273 // escape the data or add a prefix. There's probably a more graceful
1274 // way to deal with this, but I'm not thinking of it -- Rick
1275 if (strpos($item, '(') !== FALSE)
1277 return $item.$alias;
1280 // Break the string apart if it contains periods, then insert the table prefix
1281 // in the correct location, assuming the period doesn't indicate that we're dealing
1282 // with an alias. While we're at it, we will escape the components
1283 if (strpos($item, '.') !== FALSE)
1285 $parts = explode('.', $item);
1287 // Does the first segment of the exploded item match
1288 // one of the aliases previously identified? If so,
1289 // we have nothing more to do other than escape the item
1290 if (in_array($parts[0], $this->ar_aliased_tables))
1292 if ($protect_identifiers === TRUE)
1294 foreach ($parts as $key => $val)
1296 if ( ! in_array($val, $this->_reserved_identifiers))
1298 $parts[$key] = $this->_escape_identifiers($val);
1302 $item = implode('.', $parts);
1304 return $item.$alias;
1307 // Is there a table prefix defined in the config file? If not, no need to do anything
1308 if ($this->dbprefix != '')
1310 // We now add the table prefix based on some logic.
1311 // Do we have 4 segments (hostname.database.table.column)?
1312 // If so, we add the table prefix to the column name in the 3rd segment.
1313 if (isset($parts[3]))
1317 // Do we have 3 segments (database.table.column)?
1318 // If so, we add the table prefix to the column name in 2nd position
1319 elseif (isset($parts[2]))
1323 // Do we have 2 segments (table.column)?
1324 // If so, we add the table prefix to the column name in 1st segment
1330 // This flag is set when the supplied $item does not contain a field name.
1331 // This can happen when this function is being called from a JOIN.
1332 if ($field_exists == FALSE)
1337 // Verify table prefix and replace if necessary
1338 if ($this->swap_pre != '' && strncmp($parts[$i], $this->swap_pre, strlen($this->swap_pre)) === 0)
1340 $parts[$i] = preg_replace("/^".$this->swap_pre."(\S+?)/", $this->dbprefix."\\1", $parts[$i]);
1343 // We only add the table prefix if it does not already exist
1344 if (substr($parts[$i], 0, strlen($this->dbprefix)) != $this->dbprefix)
1346 $parts[$i] = $this->dbprefix.$parts[$i];
1349 // Put the parts back together
1350 $item = implode('.', $parts);
1353 if ($protect_identifiers === TRUE)
1355 $item = $this->_escape_identifiers($item);
1358 return $item.$alias;
1361 // Is there a table prefix? If not, no need to insert it
1362 if ($this->dbprefix != '')
1364 // Verify table prefix and replace if necessary
1365 if ($this->swap_pre != '' && strncmp($item, $this->swap_pre, strlen($this->swap_pre)) === 0)
1367 $item = preg_replace("/^".$this->swap_pre."(\S+?)/", $this->dbprefix."\\1", $item);
1370 // Do we prefix an item with no segments?
1371 if ($prefix_single == TRUE AND substr($item, 0, strlen($this->dbprefix)) != $this->dbprefix)
1373 $item = $this->dbprefix.$item;
1377 if ($protect_identifiers === TRUE AND ! in_array($item, $this->_reserved_identifiers))
1379 $item = $this->_escape_identifiers($item);
1382 return $item.$alias;
1389 /* End of file DB_driver.php */
1390 /* Location: ./system/database/DB_driver.php */