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moodle_database.php
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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Abstract database driver class.
*
* @package core
* @category dml
* @subpackage dml
* @copyright 2008 Petr Skoda (http://skodak.org)
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
require_once($CFG->libdir.'/dml/database_column_info.php');
require_once($CFG->libdir.'/dml/moodle_recordset.php');
require_once($CFG->libdir.'/dml/moodle_transaction.php');
/// GLOBAL CONSTANTS /////////////////////////////////////////////////////////
/** SQL_PARAMS_NAMED - Bitmask, indicates :name type parameters are supported by db backend. */
define('SQL_PARAMS_NAMED', 1);
/** SQL_PARAMS_QM - Bitmask, indicates ? type parameters are supported by db backend. */
define('SQL_PARAMS_QM', 2);
/** SQL_PARAMS_DOLLAR - Bitmask, indicates $1, $2, ... type parameters are supported by db backend. */
define('SQL_PARAMS_DOLLAR', 4);
/** SQL_QUERY_SELECT - Normal select query, reading only. */
define('SQL_QUERY_SELECT', 1);
/** SQL_QUERY_INSERT - Insert select query, writing. */
define('SQL_QUERY_INSERT', 2);
/** SQL_QUERY_UPDATE - Update select query, writing. */
define('SQL_QUERY_UPDATE', 3);
/** SQL_QUERY_STRUCTURE - Query changing db structure, writing. */
define('SQL_QUERY_STRUCTURE', 4);
/** SQL_QUERY_AUX - Auxiliary query done by driver, setting connection config, getting table info, etc. */
define('SQL_QUERY_AUX', 5);
/**
* Abstract class representing moodle database interface.
* @link http://docs.moodle.org/dev/DML_functions
*
* @package core
* @category dml
* @copyright 2008 Petr Skoda (http://skodak.org)
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class moodle_database {
/** @var database_manager db manager which allows db structure modifications. */
protected $database_manager;
/** @var moodle_temptables temptables manager to provide cross-db support for temp tables. */
protected $temptables;
/** @var array Cache of column info. */
protected $columns = array(); // I wish we had a shared memory cache for this :-(
/** @var array Cache of table info. */
protected $tables = null;
// db connection options
/** @var string db host name. */
protected $dbhost;
/** @var string db host user. */
protected $dbuser;
/** @var string db host password. */
protected $dbpass;
/** @var string db name. */
protected $dbname;
/** @var string Prefix added to table names. */
protected $prefix;
/** @var array Database or driver specific options, such as sockets or TCPIP db connections. */
protected $dboptions;
/** @var bool True means non-moodle external database used.*/
protected $external;
/** @var int The database reads (performance counter).*/
protected $reads = 0;
/** @var int The database writes (performance counter).*/
protected $writes = 0;
/** @var int Debug level. */
protected $debug = 0;
/** @var string Last used query sql. */
protected $last_sql;
/** @var array Last query parameters. */
protected $last_params;
/** @var int Last query type. */
protected $last_type;
/** @var string Last extra info. */
protected $last_extrainfo;
/** @var float Last time in seconds with millisecond precision. */
protected $last_time;
/** @var bool Flag indicating logging of query in progress. This helps prevent infinite loops. */
private $loggingquery = false;
/** @var bool True if the db is used for db sessions. */
protected $used_for_db_sessions = false;
/** @var array Array containing open transactions. */
private $transactions = array();
/** @var bool Flag used to force rollback of all current transactions. */
private $force_rollback = false;
/**
* @var int internal temporary variable used to fix params. Its used by {@link _fix_sql_params_dollar_callback()}.
*/
private $fix_sql_params_i;
/**
* @var int internal temporary variable used to guarantee unique parameters in each request. Its used by {@link get_in_or_equal()}.
*/
private $inorequaluniqueindex = 1;
/**
* Constructor - Instantiates the database, specifying if it's external (connect to other systems) or not (Moodle DB).
* Note that this affects the decision of whether prefix checks must be performed or not.
* @param bool $external True means that an external database is used.
*/
public function __construct($external=false) {
$this->external = $external;
}
/**
* Destructor - cleans up and flushes everything needed.
*/
public function __destruct() {
$this->dispose();
}
/**
* Detects if all needed PHP stuff are installed for DB connectivity.
* Note: can be used before connect()
* @return mixed True if requirements are met, otherwise a string if something isn't installed.
*/
public abstract function driver_installed();
/**
* Returns database table prefix
* Note: can be used before connect()
* @return string The prefix used in the database.
*/
public function get_prefix() {
return $this->prefix;
}
/**
* Loads and returns a database instance with the specified type and library.
*
* The loaded class is within lib/dml directory and of the form: $type.'_'.$library.'_moodle_database'
*
* @param string $type Database driver's type. (eg: mysqli, pgsql, mssql, sqldrv, oci, etc.)
* @param string $library Database driver's library (native, pdo, etc.)
* @param bool $external True if this is an external database.
* @return moodle_database driver object or null if error, for example of driver object see {@link mysqli_native_moodle_database}
*/
public static function get_driver_instance($type, $library, $external = false) {
global $CFG;
$classname = $type.'_'.$library.'_moodle_database';
$libfile = "$CFG->libdir/dml/$classname.php";
if (!file_exists($libfile)) {
return null;
}
require_once($libfile);
return new $classname($external);
}
/**
* Returns the database family type. (This sort of describes the SQL 'dialect')
* Note: can be used before connect()
* @return string The db family name (mysql, postgres, mssql, oracle, etc.)
*/
public abstract function get_dbfamily();
/**
* Returns a more specific database driver type
* Note: can be used before connect()
* @return string The db type mysqli, pgsql, oci, mssql, sqlsrv
*/
protected abstract function get_dbtype();
/**
* Returns the general database library name
* Note: can be used before connect()
* @return string The db library type - pdo, native etc.
*/
protected abstract function get_dblibrary();
/**
* Returns the localised database type name
* Note: can be used before connect()
* @return string
*/
public abstract function get_name();
/**
* Returns the localised database configuration help.
* Note: can be used before connect()
* @return string
*/
public abstract function get_configuration_help();
/**
* Returns the localised database description
* Note: can be used before connect()
* @return string
*/
public abstract function get_configuration_hints();
/**
* Returns the db related part of config.php
* @return stdClass
*/
public function export_dbconfig() {
$cfg = new stdClass();
$cfg->dbtype = $this->get_dbtype();
$cfg->dblibrary = $this->get_dblibrary();
$cfg->dbhost = $this->dbhost;
$cfg->dbname = $this->dbname;
$cfg->dbuser = $this->dbuser;
$cfg->dbpass = $this->dbpass;
$cfg->prefix = $this->prefix;
if ($this->dboptions) {
$cfg->dboptions = $this->dboptions;
}
return $cfg;
}
/**
* Diagnose database and tables, this function is used
* to verify database and driver settings, db engine types, etc.
*
* @return string null means everything ok, string means problem found.
*/
public function diagnose() {
return null;
}
/**
* Connects to the database.
* Must be called before other methods.
* @param string $dbhost The database host.
* @param string $dbuser The database user to connect as.
* @param string $dbpass The password to use when connecting to the database.
* @param string $dbname The name of the database being connected to.
* @param mixed $prefix string means moodle db prefix, false used for external databases where prefix not used
* @param array $dboptions driver specific options
* @return bool true
* @throws dml_connection_exception if error
*/
public abstract function connect($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null);
/**
* Store various database settings
* @param string $dbhost The database host.
* @param string $dbuser The database user to connect as.
* @param string $dbpass The password to use when connecting to the database.
* @param string $dbname The name of the database being connected to.
* @param mixed $prefix string means moodle db prefix, false used for external databases where prefix not used
* @param array $dboptions driver specific options
* @return void
*/
protected function store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null) {
$this->dbhost = $dbhost;
$this->dbuser = $dbuser;
$this->dbpass = $dbpass;
$this->dbname = $dbname;
$this->prefix = $prefix;
$this->dboptions = (array)$dboptions;
}
/**
* Attempt to create the database
* @param string $dbhost The database host.
* @param string $dbuser The database user to connect as.
* @param string $dbpass The password to use when connecting to the database.
* @param string $dbname The name of the database being connected to.
* @param array $dboptions An array of optional database options (eg: dbport)
*
* @return bool success True for successful connection. False otherwise.
*/
public function create_database($dbhost, $dbuser, $dbpass, $dbname, array $dboptions=null) {
return false;
}
/**
* Closes the database connection and releases all resources
* and memory (especially circular memory references).
* Do NOT use connect() again, create a new instance if needed.
* @return void
*/
public function dispose() {
if ($this->transactions) {
// this should not happen, it usually indicates wrong catching of exceptions,
// because all transactions should be finished manually or in default exception handler.
// unfortunately we can not access global $CFG any more and can not print debug,
// the diagnostic info should be printed in footer instead
$lowesttransaction = end($this->transactions);
$backtrace = $lowesttransaction->get_backtrace();
error_log('Potential coding error - active database transaction detected when disposing database:'."\n".format_backtrace($backtrace, true));
$this->force_transaction_rollback();
}
if ($this->used_for_db_sessions) {
// this is needed because we need to save session to db before closing it
session_get_instance()->write_close();
$this->used_for_db_sessions = false;
}
if ($this->temptables) {
$this->temptables->dispose();
$this->temptables = null;
}
if ($this->database_manager) {
$this->database_manager->dispose();
$this->database_manager = null;
}
$this->columns = array();
$this->tables = null;
}
/**
* This should be called before each db query.
* @param string $sql The query string.
* @param array $params An array of parameters.
* @param int $type The type of query. ( SQL_QUERY_SELECT | SQL_QUERY_AUX | SQL_QUERY_INSERT | SQL_QUERY_UPDATE | SQL_QUERY_STRUCTURE )
* @param mixed $extrainfo This is here for any driver specific extra information.
* @return void
*/
protected function query_start($sql, array $params=null, $type, $extrainfo=null) {
if ($this->loggingquery) {
return;
}
$this->last_sql = $sql;
$this->last_params = $params;
$this->last_type = $type;
$this->last_extrainfo = $extrainfo;
$this->last_time = microtime(true);
switch ($type) {
case SQL_QUERY_SELECT:
case SQL_QUERY_AUX:
$this->reads++;
break;
case SQL_QUERY_INSERT:
case SQL_QUERY_UPDATE:
case SQL_QUERY_STRUCTURE:
$this->writes++;
}
$this->print_debug($sql, $params);
}
/**
* This should be called immediately after each db query. It does a clean up of resources.
* It also throws exceptions if the sql that ran produced errors.
* @param mixed $result The db specific result obtained from running a query.
* @throws dml_read_exception | dml_write_exception | ddl_change_structure_exception
* @return void
*/
protected function query_end($result) {
if ($this->loggingquery) {
return;
}
if ($result !== false) {
$this->query_log();
// free memory
$this->last_sql = null;
$this->last_params = null;
return;
}
// remember current info, log queries may alter it
$type = $this->last_type;
$sql = $this->last_sql;
$params = $this->last_params;
$time = microtime(true) - $this->last_time;
$error = $this->get_last_error();
$this->query_log($error);
switch ($type) {
case SQL_QUERY_SELECT:
case SQL_QUERY_AUX:
throw new dml_read_exception($error, $sql, $params);
case SQL_QUERY_INSERT:
case SQL_QUERY_UPDATE:
throw new dml_write_exception($error, $sql, $params);
case SQL_QUERY_STRUCTURE:
$this->get_manager(); // includes ddl exceptions classes ;-)
throw new ddl_change_structure_exception($error, $sql);
}
}
/**
* This logs the last query based on 'logall', 'logslow' and 'logerrors' options configured via $CFG->dboptions .
* @param mixed string error or false if not error
* @return void
*/
public function query_log($error=false) {
$logall = !empty($this->dboptions['logall']);
$logslow = !empty($this->dboptions['logslow']) ? $this->dboptions['logslow'] : false;
$logerrors = !empty($this->dboptions['logerrors']);
$iserror = ($error !== false);
$time = microtime(true) - $this->last_time;
if ($logall or ($logslow and ($logslow < ($time+0.00001))) or ($iserror and $logerrors)) {
$this->loggingquery = true;
try {
$backtrace = debug_backtrace();
if ($backtrace) {
//remove query_log()
array_shift($backtrace);
}
if ($backtrace) {
//remove query_end()
array_shift($backtrace);
}
$log = new stdClass();
$log->qtype = $this->last_type;
$log->sqltext = $this->last_sql;
$log->sqlparams = var_export((array)$this->last_params, true);
$log->error = (int)$iserror;
$log->info = $iserror ? $error : null;
$log->backtrace = format_backtrace($backtrace, true);
$log->exectime = $time;
$log->timelogged = time();
$this->insert_record('log_queries', $log);
} catch (Exception $ignored) {
}
$this->loggingquery = false;
}
}
/**
* Returns database server info array
* @return array Array containing 'description' and 'version' atleast.
*/
public abstract function get_server_info();
/**
* Returns supported query parameter types
* @return int bitmask of accepted SQL_PARAMS_*
*/
protected abstract function allowed_param_types();
/**
* Returns the last error reported by the database engine.
* @return string The error message.
*/
public abstract function get_last_error();
/**
* Prints sql debug info
* @param string $sql The query which is being debugged.
* @param array $params The query parameters. (optional)
* @param mixed $obj The library specific object. (optional)
* @return void
*/
protected function print_debug($sql, array $params=null, $obj=null) {
if (!$this->get_debug()) {
return;
}
if (CLI_SCRIPT) {
echo "--------------------------------\n";
echo $sql."\n";
if (!is_null($params)) {
echo "[".var_export($params, true)."]\n";
}
echo "--------------------------------\n";
} else {
echo "<hr />\n";
echo s($sql)."\n";
if (!is_null($params)) {
echo "[".s(var_export($params, true))."]\n";
}
echo "<hr />\n";
}
}
/**
* Returns the SQL WHERE conditions.
* @param string $table The table name that these conditions will be validated against.
* @param array $conditions The conditions to build the where clause. (must not contain numeric indexes)
* @throws dml_exception
* @return array An array list containing sql 'where' part and 'params'.
*/
protected function where_clause($table, array $conditions=null) {
// We accept nulls in conditions
$conditions = is_null($conditions) ? array() : $conditions;
// Some checks performed under debugging only
if (debugging()) {
$columns = $this->get_columns($table);
if (empty($columns)) {
// no supported columns means most probably table does not exist
throw new dml_exception('ddltablenotexist', $table);
}
foreach ($conditions as $key=>$value) {
if (!isset($columns[$key])) {
$a = new stdClass();
$a->fieldname = $key;
$a->tablename = $table;
throw new dml_exception('ddlfieldnotexist', $a);
}
$column = $columns[$key];
if ($column->meta_type == 'X') {
//ok so the column is a text column. sorry no text columns in the where clause conditions
throw new dml_exception('textconditionsnotallowed', $conditions);
}
}
}
$allowed_types = $this->allowed_param_types();
if (empty($conditions)) {
return array('', array());
}
$where = array();
$params = array();
foreach ($conditions as $key=>$value) {
if (is_int($key)) {
throw new dml_exception('invalidnumkey');
}
if (is_null($value)) {
$where[] = "$key IS NULL";
} else {
if ($allowed_types & SQL_PARAMS_NAMED) {
// Need to verify key names because they can contain, originally,
// spaces and other forbidden chars when using sql_xxx() functions and friends.
$normkey = trim(preg_replace('/[^a-zA-Z0-9_-]/', '_', $key), '-_');
if ($normkey !== $key) {
debugging('Invalid key found in the conditions array.');
}
$where[] = "$key = :$normkey";
$params[$normkey] = $value;
} else {
$where[] = "$key = ?";
$params[] = $value;
}
}
}
$where = implode(" AND ", $where);
return array($where, $params);
}
/**
* Returns SQL WHERE conditions for the ..._list group of methods.
*
* @param string $field the name of a field.
* @param array $values the values field might take.
* @return array An array containing sql 'where' part and 'params'
*/
protected function where_clause_list($field, array $values) {
$params = array();
$select = array();
$values = (array)$values;
foreach ($values as $value) {
if (is_bool($value)) {
$value = (int)$value;
}
if (is_null($value)) {
$select[] = "$field IS NULL";
} else {
$select[] = "$field = ?";
$params[] = $value;
}
}
$select = implode(" OR ", $select);
return array($select, $params);
}
/**
* Constructs 'IN()' or '=' sql fragment
* @param mixed $items A single value or array of values for the expression.
* @param int $type Parameter bounding type : SQL_PARAMS_QM or SQL_PARAMS_NAMED.
* @param string $prefix Named parameter placeholder prefix (a unique counter value is appended to each parameter name).
* @param bool $equal True means we want to equate to the constructed expression, false means we don't want to equate to it.
* @param mixed $onemptyitems This defines the behavior when the array of items provided is empty. Defaults to false,
* meaning throw exceptions. Other values will become part of the returned SQL fragment.
* @throws coding_exception | dml_exception
* @return array A list containing the constructed sql fragment and an array of parameters.
*/
public function get_in_or_equal($items, $type=SQL_PARAMS_QM, $prefix='param', $equal=true, $onemptyitems=false) {
// default behavior, throw exception on empty array
if (is_array($items) and empty($items) and $onemptyitems === false) {
throw new coding_exception('moodle_database::get_in_or_equal() does not accept empty arrays');
}
// handle $onemptyitems on empty array of items
if (is_array($items) and empty($items)) {
if (is_null($onemptyitems)) { // Special case, NULL value
$sql = $equal ? ' IS NULL' : ' IS NOT NULL';
return (array($sql, array()));
} else {
$items = array($onemptyitems); // Rest of cases, prepare $items for std processing
}
}
if ($type == SQL_PARAMS_QM) {
if (!is_array($items) or count($items) == 1) {
$sql = $equal ? '= ?' : '<> ?';
$items = (array)$items;
$params = array_values($items);
} else {
if ($equal) {
$sql = 'IN ('.implode(',', array_fill(0, count($items), '?')).')';
} else {
$sql = 'NOT IN ('.implode(',', array_fill(0, count($items), '?')).')';
}
$params = array_values($items);
}
} else if ($type == SQL_PARAMS_NAMED) {
if (empty($prefix)) {
$prefix = 'param';
}
if (!is_array($items)){
$param = $prefix.$this->inorequaluniqueindex++;
$sql = $equal ? "= :$param" : "<> :$param";
$params = array($param=>$items);
} else if (count($items) == 1) {
$param = $prefix.$this->inorequaluniqueindex++;
$sql = $equal ? "= :$param" : "<> :$param";
$item = reset($items);
$params = array($param=>$item);
} else {
$params = array();
$sql = array();
foreach ($items as $item) {
$param = $prefix.$this->inorequaluniqueindex++;
$params[$param] = $item;
$sql[] = ':'.$param;
}
if ($equal) {
$sql = 'IN ('.implode(',', $sql).')';
} else {
$sql = 'NOT IN ('.implode(',', $sql).')';
}
}
} else {
throw new dml_exception('typenotimplement');
}
return array($sql, $params);
}
/**
* Converts short table name {tablename} to the real prefixed table name in given sql.
* @param string $sql The sql to be operated on.
* @return string The sql with tablenames being prefixed with $CFG->prefix
*/
protected function fix_table_names($sql) {
return preg_replace('/\{([a-z][a-z0-9_]*)\}/', $this->prefix.'$1', $sql);
}
/**
* Internal private utitlity function used to fix parameters.
* Used with {@link preg_replace_callback()}
* @param array $match Refer to preg_replace_callback usage for description.
*/
private function _fix_sql_params_dollar_callback($match) {
$this->fix_sql_params_i++;
return "\$".$this->fix_sql_params_i;
}
/**
* Detects object parameters and throws exception if found
* @param mixed $value
* @return void
*/
protected function detect_objects($value) {
if (is_object($value)) {
throw new coding_exception('Invalid database query parameter value', 'Objects are are not allowed: '.get_class($value));
}
}
/**
* Normalizes sql query parameters and verifies parameters.
* @param string $sql The query or part of it.
* @param array $params The query parameters.
* @return array (sql, params, type of params)
*/
public function fix_sql_params($sql, array $params=null) {
$params = (array)$params; // mke null array if needed
$allowed_types = $this->allowed_param_types();
// convert table names
$sql = $this->fix_table_names($sql);
// cast booleans to 1/0 int and detect forbidden objects
foreach ($params as $key => $value) {
$this->detect_objects($value);
$params[$key] = is_bool($value) ? (int)$value : $value;
}
// NICOLAS C: Fixed regexp for negative backwards lookahead of double colons. Thanks for Sam Marshall's help
$named_count = preg_match_all('/(?<!:):[a-z][a-z0-9_]*/', $sql, $named_matches); // :: used in pgsql casts
$dollar_count = preg_match_all('/\$[1-9][0-9]*/', $sql, $dollar_matches);
$q_count = substr_count($sql, '?');
$count = 0;
if ($named_count) {
$type = SQL_PARAMS_NAMED;
$count = $named_count;
}
if ($dollar_count) {
if ($count) {
throw new dml_exception('mixedtypesqlparam');
}
$type = SQL_PARAMS_DOLLAR;
$count = $dollar_count;
}
if ($q_count) {
if ($count) {
throw new dml_exception('mixedtypesqlparam');
}
$type = SQL_PARAMS_QM;
$count = $q_count;
}
if (!$count) {
// ignore params
if ($allowed_types & SQL_PARAMS_NAMED) {
return array($sql, array(), SQL_PARAMS_NAMED);
} else if ($allowed_types & SQL_PARAMS_QM) {
return array($sql, array(), SQL_PARAMS_QM);
} else {
return array($sql, array(), SQL_PARAMS_DOLLAR);
}
}
if ($count > count($params)) {
$a = new stdClass;
$a->expected = $count;
$a->actual = count($params);
throw new dml_exception('invalidqueryparam', $a);
}
$target_type = $allowed_types;
if ($type & $allowed_types) { // bitwise AND
if ($count == count($params)) {
if ($type == SQL_PARAMS_QM) {
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based array required
} else {
//better do the validation of names below
}
}
// needs some fixing or validation - there might be more params than needed
$target_type = $type;
}
if ($type == SQL_PARAMS_NAMED) {
$finalparams = array();
foreach ($named_matches[0] as $key) {
$key = trim($key, ':');
if (!array_key_exists($key, $params)) {
throw new dml_exception('missingkeyinsql', $key, '');
}
if (strlen($key) > 30) {
throw new coding_exception(
"Placeholder names must be 30 characters or shorter. '" .
$key . "' is too long.", $sql);
}
$finalparams[$key] = $params[$key];
}
if ($count != count($finalparams)) {
throw new dml_exception('duplicateparaminsql');
}
if ($target_type & SQL_PARAMS_QM) {
$sql = preg_replace('/(?<!:):[a-z][a-z0-9_]*/', '?', $sql);
return array($sql, array_values($finalparams), SQL_PARAMS_QM); // 0-based required
} else if ($target_type & SQL_PARAMS_NAMED) {
return array($sql, $finalparams, SQL_PARAMS_NAMED);
} else { // $type & SQL_PARAMS_DOLLAR
//lambda-style functions eat memory - we use globals instead :-(
$this->fix_sql_params_i = 0;
$sql = preg_replace_callback('/(?<!:):[a-z][a-z0-9_]*/', array($this, '_fix_sql_params_dollar_callback'), $sql);
return array($sql, array_values($finalparams), SQL_PARAMS_DOLLAR); // 0-based required
}
} else if ($type == SQL_PARAMS_DOLLAR) {
if ($target_type & SQL_PARAMS_DOLLAR) {
return array($sql, array_values($params), SQL_PARAMS_DOLLAR); // 0-based required
} else if ($target_type & SQL_PARAMS_QM) {
$sql = preg_replace('/\$[0-9]+/', '?', $sql);
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based required
} else { //$target_type & SQL_PARAMS_NAMED
$sql = preg_replace('/\$([0-9]+)/', ':param\\1', $sql);
$finalparams = array();
foreach ($params as $key=>$param) {
$key++;
$finalparams['param'.$key] = $param;
}
return array($sql, $finalparams, SQL_PARAMS_NAMED);
}
} else { // $type == SQL_PARAMS_QM
if (count($params) != $count) {
$params = array_slice($params, 0, $count);
}
if ($target_type & SQL_PARAMS_QM) {
return array($sql, array_values($params), SQL_PARAMS_QM); // 0-based required
} else if ($target_type & SQL_PARAMS_NAMED) {
$finalparams = array();
$pname = 'param0';
$parts = explode('?', $sql);
$sql = array_shift($parts);
foreach ($parts as $part) {
$param = array_shift($params);
$pname++;
$sql .= ':'.$pname.$part;
$finalparams[$pname] = $param;
}
return array($sql, $finalparams, SQL_PARAMS_NAMED);
} else { // $type & SQL_PARAMS_DOLLAR
//lambda-style functions eat memory - we use globals instead :-(
$this->fix_sql_params_i = 0;
$sql = preg_replace_callback('/\?/', array($this, '_fix_sql_params_dollar_callback'), $sql);
return array($sql, array_values($params), SQL_PARAMS_DOLLAR); // 0-based required
}
}
}
/**
* Return tables in database WITHOUT current prefix.
* @param bool $usecache if true, returns list of cached tables.
* @return array of table names in lowercase and without prefix
*/
public abstract function get_tables($usecache=true);
/**
* Return table indexes - everything lowercased.
* @param string $table The table we want to get indexes from.
* @return array An associative array of indexes containing 'unique' flag and 'columns' being indexed
*/
public abstract function get_indexes($table);
/**
* Returns detailed information about columns in table. This information is cached internally.
* @param string $table The table's name.
* @param bool $usecache Flag to use internal cacheing. The default is true.
* @return array of database_column_info objects indexed with column names
*/
public abstract function get_columns($table, $usecache=true);
/**
* Normalise values based on varying RDBMS's dependencies (booleans, LOBs...)
*
* @param database_column_info $column column metadata corresponding with the value we are going to normalise
* @param mixed $value value we are going to normalise
* @return mixed the normalised value
*/
protected abstract function normalise_value($column, $value);
/**
* Resets the internal column details cache
* @return void
*/
public function reset_caches() {
$this->columns = array();
$this->tables = null;
}
/**
* Returns the sql generator used for db manipulation.
* Used mostly in upgrade.php scripts.
* @return database_manager The instance used to perform ddl operations.
* @see lib/ddl/database_manager.php
*/
public function get_manager() {
global $CFG;
if (!$this->database_manager) {
require_once($CFG->libdir.'/ddllib.php');
$classname = $this->get_dbfamily().'_sql_generator';
require_once("$CFG->libdir/ddl/$classname.php");
$generator = new $classname($this, $this->temptables);
$this->database_manager = new database_manager($this, $generator);
}
return $this->database_manager;
}
/**
* Attempts to change db encoding to UTF-8 encoding if possible.
* @return bool True is successful.
*/
public function change_db_encoding() {
return false;
}
/**
* Checks to see if the database is in unicode mode?
* @return bool
*/
public function setup_is_unicodedb() {
return true;
}
/**
* Enable/disable very detailed debugging.
* @param bool $state
* @return void
*/
public function set_debug($state) {
$this->debug = $state;
}
/**
* Returns debug status
* @return bool $state
*/
public function get_debug() {
return $this->debug;
}
/**
* Enable/disable detailed sql logging
* @param bool $state
*/
public function set_logging($state) {
// adodb sql logging shares one table without prefix per db - this is no longer acceptable :-(
// we must create one table shared by all drivers
}
/**
* Do NOT use in code, this is for use by database_manager only!
* @param string $sql query
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public abstract function change_database_structure($sql);
/**
* Executes a general sql query. Should be used only when no other method suitable.
* Do NOT use this to make changes in db structure, use database_manager methods instead!
* @param string $sql query
* @param array $params query parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public abstract function execute($sql, array $params=null);
/**
* Get a number of records as a moodle_recordset where all the given conditions met.
*
* Selects records from the table $table.
*
* If specified, only records meeting $conditions.
*
* If specified, the results will be sorted as specified by $sort. This
* is added to the SQL as "ORDER BY $sort". Example values of $sort
* might be "time ASC" or "time DESC".
*
* If $fields is specified, only those fields are returned.
*
* Since this method is a little less readable, use of it should be restricted to
* code where it's possible there might be large datasets being returned. For known
* small datasets use get_records - it leads to simpler code.
*
* If you only want some of the records, specify $limitfrom and $limitnum.
* The query will skip the first $limitfrom records (according to the sort
* order) and then return the next $limitnum records. If either of $limitfrom
* or $limitnum is specified, both must be present.
*