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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/>.
/**
* Native oci class representing moodle database interface.
*
* @package core_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(__DIR__.'/moodle_database.php');
require_once(__DIR__.'/oci_native_moodle_recordset.php');
require_once(__DIR__.'/oci_native_moodle_temptables.php');
/**
* Native oci class representing moodle database interface.
*
* One complete reference for PHP + OCI:
* http://www.oracle.com/technology/tech/php/underground-php-oracle-manual.html
*
* @package core_dml
* @copyright 2008 Petr Skoda (http://skodak.org)
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class oci_native_moodle_database extends moodle_database {
protected $oci = null;
/** @var To store stmt errors and enable get_last_error() to detect them.*/
private $last_stmt_error = null;
/** @var Default value initialised in connect method, we need the driver to be present.*/
private $commit_status = null;
/** @var To handle oci driver default verbosity.*/
private $last_error_reporting;
/** @var To store unique_session_id. Needed for temp tables unique naming.*/
private $unique_session_id;
/**
* Detects if all needed PHP stuff installed.
* Note: can be used before connect()
* @return mixed true if ok, string if something
*/
public function driver_installed() {
if (!extension_loaded('oci8')) {
return get_string('ociextensionisnotpresentinphp', 'install');
}
return true;
}
/**
* Returns database family type - describes SQL dialect
* Note: can be used before connect()
* @return string db family name (mysql, postgres, mssql, oracle, etc.)
*/
public function get_dbfamily() {
return 'oracle';
}
/**
* Returns more specific database driver type
* Note: can be used before connect()
* @return string db type mysqli, pgsql, oci, mssql, sqlsrv
*/
protected function get_dbtype() {
return 'oci';
}
/**
* Returns general database library name
* Note: can be used before connect()
* @return string db type pdo, native
*/
protected function get_dblibrary() {
return 'native';
}
/**
* Returns localised database type name
* Note: can be used before connect()
* @return string
*/
public function get_name() {
return get_string('nativeoci', 'install');
}
/**
* Returns localised database configuration help.
* Note: can be used before connect()
* @return string
*/
public function get_configuration_help() {
return get_string('nativeocihelp', 'install');
}
/**
* 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;
}
/**
* Connect to db
* Must be called before other methods.
* @param string $dbhost The database host.
* @param string $dbuser The database username.
* @param string $dbpass The database username's password.
* @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 $dboptions driver specific options
* @return bool true
* @throws dml_connection_exception if error
*/
public function connect($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null) {
if ($prefix == '' and !$this->external) {
//Enforce prefixes for everybody but mysql
throw new dml_exception('prefixcannotbeempty', $this->get_dbfamily());
}
if (!$this->external and strlen($prefix) > 2) {
//Max prefix length for Oracle is 2cc
$a = (object)array('dbfamily'=>'oracle', 'maxlength'=>2);
throw new dml_exception('prefixtoolong', $a);
}
$driverstatus = $this->driver_installed();
if ($driverstatus !== true) {
throw new dml_exception('dbdriverproblem', $driverstatus);
}
// Autocommit ON by default.
// Switching to OFF (OCI_DEFAULT), when playing with transactions
// please note this thing is not defined if oracle driver not present in PHP
// which means it can not be used as default value of object property!
$this->commit_status = OCI_COMMIT_ON_SUCCESS;
$this->store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, $dboptions);
unset($this->dboptions['dbsocket']);
// NOTE: use of ', ", / and \ is very problematic, even native oracle tools seem to have
// problems with these, so just forget them and do not report problems into tracker...
if (empty($this->dbhost)) {
// old style full address (TNS)
$dbstring = $this->dbname;
} else {
if (empty($this->dboptions['dbport'])) {
$this->dboptions['dbport'] = 1521;
}
$dbstring = '//'.$this->dbhost.':'.$this->dboptions['dbport'].'/'.$this->dbname;
}
ob_start();
if (empty($this->dboptions['dbpersist'])) {
$this->oci = oci_new_connect($this->dbuser, $this->dbpass, $dbstring, 'AL32UTF8');
} else {
$this->oci = oci_pconnect($this->dbuser, $this->dbpass, $dbstring, 'AL32UTF8');
}
$dberr = ob_get_contents();
ob_end_clean();
if ($this->oci === false) {
$this->oci = null;
$e = oci_error();
if (isset($e['message'])) {
$dberr = $e['message'];
}
throw new dml_connection_exception($dberr);
}
// Disable logging until we are fully setup.
$this->query_log_prevent();
// Make sure moodle package is installed - now required.
if (!$this->oci_package_installed()) {
try {
$this->attempt_oci_package_install();
} catch (Exception $e) {
// Ignore problems, only the result counts,
// admins have to fix it manually if necessary.
}
if (!$this->oci_package_installed()) {
throw new dml_exception('dbdriverproblem', 'Oracle PL/SQL Moodle support package MOODLELIB is not installed! Database administrator has to execute /lib/dml/oci_native_moodle_package.sql script.');
}
}
// get unique session id, to be used later for temp tables stuff
$sql = 'SELECT DBMS_SESSION.UNIQUE_SESSION_ID() FROM DUAL';
$this->query_start($sql, null, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_ROW);
oci_free_statement($stmt);
$this->unique_session_id = reset($records[0]);
//note: do not send "ALTER SESSION SET NLS_NUMERIC_CHARACTERS='.,'" !
// instead fix our PHP code to convert "," to "." properly!
// We can enable logging now.
$this->query_log_allow();
// Connection stabilised and configured, going to instantiate the temptables controller
$this->temptables = new oci_native_moodle_temptables($this, $this->unique_session_id);
return true;
}
/**
* Close database connection and release all resources
* and memory (especially circular memory references).
* Do NOT use connect() again, create a new instance if needed.
*/
public function dispose() {
parent::dispose(); // Call parent dispose to write/close session and other common stuff before closing connection
if ($this->oci) {
oci_close($this->oci);
$this->oci = null;
}
}
/**
* Called before each db query.
* @param string $sql
* @param array array of parameters
* @param int $type type of query
* @param mixed $extrainfo driver specific extra information
* @return void
*/
protected function query_start($sql, array $params=null, $type, $extrainfo=null) {
parent::query_start($sql, $params, $type, $extrainfo);
// oci driver tents to send debug to output, we do not need that ;-)
$this->last_error_reporting = error_reporting(0);
}
/**
* Called immediately after each db query.
* @param mixed db specific result
* @return void
*/
protected function query_end($result, $stmt=null) {
// reset original debug level
error_reporting($this->last_error_reporting);
if ($stmt and $result === false) {
// Look for stmt error and store it
if (is_resource($stmt)) {
$e = oci_error($stmt);
if ($e !== false) {
$this->last_stmt_error = $e['message'];
}
}
oci_free_statement($stmt);
}
parent::query_end($result);
}
/**
* Returns database server info array
* @return array Array containing 'description' and 'version' info
*/
public function get_server_info() {
static $info = null; // TODO: move to real object property
if (is_null($info)) {
$this->query_start("--oci_server_version()", null, SQL_QUERY_AUX);
$description = oci_server_version($this->oci);
$this->query_end(true);
preg_match('/(\d+\.)+\d+/', $description, $matches);
$info = array('description'=>$description, 'version'=>$matches[0]);
}
return $info;
}
/**
* Converts short table name {tablename} to real table name
* supporting temp tables ($this->unique_session_id based) if detected
*
* @param string sql
* @return string sql
*/
protected function fix_table_names($sql) {
if (preg_match_all('/\{([a-z][a-z0-9_]*)\}/', $sql, $matches)) {
foreach($matches[0] as $key=>$match) {
$name = $matches[1][$key];
if ($this->temptables && $this->temptables->is_temptable($name)) {
$sql = str_replace($match, $this->temptables->get_correct_name($name), $sql);
} else {
$sql = str_replace($match, $this->prefix.$name, $sql);
}
}
}
return $sql;
}
/**
* Returns supported query parameter types
* @return int bitmask of accepted SQL_PARAMS_*
*/
protected function allowed_param_types() {
return SQL_PARAMS_NAMED;
}
/**
* Returns last error reported by database engine.
* @return string error message
*/
public function get_last_error() {
$error = false;
// First look for any previously saved stmt error
if (!empty($this->last_stmt_error)) {
$error = $this->last_stmt_error;
$this->last_stmt_error = null;
} else { // Now try connection error
$e = oci_error($this->oci);
if ($e !== false) {
$error = $e['message'];
}
}
return $error;
}
/**
* Prepare the statement for execution
* @throws dml_connection_exception
* @param string $sql
* @return resource
*/
protected function parse_query($sql) {
$stmt = oci_parse($this->oci, $sql);
if ($stmt == false) {
throw new dml_connection_exception('Can not parse sql query'); //TODO: maybe add better info
}
return $stmt;
}
/**
* Make sure there are no reserved words in param names...
* @param string $sql
* @param array $params
* @return array ($sql, $params) updated query and parameters
*/
protected function tweak_param_names($sql, array $params) {
if (empty($params)) {
return array($sql, $params);
}
$newparams = array();
$searcharr = array(); // search => replace pairs
foreach ($params as $name => $value) {
// Keep the name within the 30 chars limit always (prefixing/replacing)
if (strlen($name) <= 28) {
$newname = 'o_' . $name;
} else {
$newname = 'o_' . substr($name, 2);
}
$newparams[$newname] = $value;
$searcharr[':' . $name] = ':' . $newname;
}
// sort by length desc to avoid potential str_replace() overlap
uksort($searcharr, array('oci_native_moodle_database', 'compare_by_length_desc'));
$sql = str_replace(array_keys($searcharr), $searcharr, $sql);
return array($sql, $newparams);
}
/**
* Return tables in database WITHOUT current prefix
* @param bool $usecache if true, returns list of cached tables.
* @return array of table names in lowercase and without prefix
*/
public function get_tables($usecache=true) {
if ($usecache and $this->tables !== null) {
return $this->tables;
}
$this->tables = array();
$prefix = str_replace('_', "\\_", strtoupper($this->prefix));
$sql = "SELECT TABLE_NAME
FROM CAT
WHERE TABLE_TYPE='TABLE'
AND TABLE_NAME NOT LIKE 'BIN\$%'
AND TABLE_NAME LIKE '$prefix%' ESCAPE '\\'";
$this->query_start($sql, null, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_ASSOC);
oci_free_statement($stmt);
$records = array_map('strtolower', $records['TABLE_NAME']);
foreach ($records as $tablename) {
if ($this->prefix !== false && $this->prefix !== '') {
if (strpos($tablename, $this->prefix) !== 0) {
continue;
}
$tablename = substr($tablename, strlen($this->prefix));
}
$this->tables[$tablename] = $tablename;
}
// Add the currently available temptables
$this->tables = array_merge($this->tables, $this->temptables->get_temptables());
return $this->tables;
}
/**
* Return table indexes - everything lowercased.
* @param string $table The table we want to get indexes from.
* @return array An associative array of indexes containing 'unique' flag and 'columns' being indexed
*/
public function get_indexes($table) {
$indexes = array();
$tablename = strtoupper($this->prefix.$table);
$sql = "SELECT i.INDEX_NAME, i.UNIQUENESS, c.COLUMN_POSITION, c.COLUMN_NAME, ac.CONSTRAINT_TYPE
FROM ALL_INDEXES i
JOIN ALL_IND_COLUMNS c ON c.INDEX_NAME=i.INDEX_NAME
LEFT JOIN ALL_CONSTRAINTS ac ON (ac.TABLE_NAME=i.TABLE_NAME AND ac.CONSTRAINT_NAME=i.INDEX_NAME AND ac.CONSTRAINT_TYPE='P')
WHERE i.TABLE_NAME = '$tablename'
ORDER BY i.INDEX_NAME, c.COLUMN_POSITION";
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_ROW);
oci_free_statement($stmt);
foreach ($records as $record) {
if ($record['CONSTRAINT_TYPE'] === 'P') {
//ignore for now;
continue;
}
$indexname = strtolower($record['INDEX_NAME']);
if (!isset($indexes[$indexname])) {
$indexes[$indexname] = array('primary' => ($record['CONSTRAINT_TYPE'] === 'P'),
'unique' => ($record['UNIQUENESS'] === 'UNIQUE'),
'columns' => array());
}
$indexes[$indexname]['columns'][] = strtolower($record['COLUMN_NAME']);
}
return $indexes;
}
/**
* Fetches detailed information about columns in table.
*
* @param string $table name
* @return array array of database_column_info objects indexed with column names
*/
protected function fetch_columns(string $table): array {
$structure = array();
// We give precedence to CHAR_LENGTH for VARCHAR2 columns over WIDTH because the former is always
// BYTE based and, for cross-db operations, we want CHAR based results. See MDL-29415
// Instead of guessing sequence based exclusively on name, check tables against user_triggers to
// ensure the table has a 'before each row' trigger to assume 'id' is auto_increment. MDL-32365
$sql = "SELECT CNAME, COLTYPE, nvl(CHAR_LENGTH, WIDTH) AS WIDTH, SCALE, PRECISION, NULLS, DEFAULTVAL,
DECODE(NVL(TRIGGER_NAME, '0'), '0', '0', '1') HASTRIGGER
FROM COL c
LEFT JOIN USER_TAB_COLUMNS u ON (u.TABLE_NAME = c.TNAME AND u.COLUMN_NAME = c.CNAME AND u.DATA_TYPE = 'VARCHAR2')
LEFT JOIN USER_TRIGGERS t ON (t.TABLE_NAME = c.TNAME AND TRIGGER_TYPE = 'BEFORE EACH ROW' AND c.CNAME = 'ID')
WHERE TNAME = UPPER('{" . $table . "}')
ORDER BY COLNO";
list($sql, $params, $type) = $this->fix_sql_params($sql, null);
$this->query_start($sql, null, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_ROW);
oci_free_statement($stmt);
if (!$records) {
return array();
}
foreach ($records as $rawcolumn) {
$rawcolumn = (object)$rawcolumn;
$info = new stdClass();
$info->name = strtolower($rawcolumn->CNAME);
$info->auto_increment = ((int)$rawcolumn->HASTRIGGER) ? true : false;
$matches = null;
if ($rawcolumn->COLTYPE === 'VARCHAR2'
or $rawcolumn->COLTYPE === 'VARCHAR'
or $rawcolumn->COLTYPE === 'NVARCHAR2'
or $rawcolumn->COLTYPE === 'NVARCHAR'
or $rawcolumn->COLTYPE === 'CHAR'
or $rawcolumn->COLTYPE === 'NCHAR') {
$info->type = $rawcolumn->COLTYPE;
$info->meta_type = 'C';
$info->max_length = $rawcolumn->WIDTH;
$info->scale = null;
$info->not_null = ($rawcolumn->NULLS === 'NOT NULL');
$info->has_default = !is_null($rawcolumn->DEFAULTVAL);
if ($info->has_default) {
// this is hacky :-(
if ($rawcolumn->DEFAULTVAL === 'NULL') {
$info->default_value = null;
} else if ($rawcolumn->DEFAULTVAL === "' ' ") { // Sometimes it's stored with trailing space
$info->default_value = "";
} else if ($rawcolumn->DEFAULTVAL === "' '") { // Sometimes it's stored without trailing space
$info->default_value = "";
} else {
$info->default_value = trim($rawcolumn->DEFAULTVAL); // remove trailing space
$info->default_value = substr($info->default_value, 1, strlen($info->default_value)-2); //trim ''
}
} else {
$info->default_value = null;
}
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->unique = null;
} else if ($rawcolumn->COLTYPE === 'NUMBER') {
$info->type = $rawcolumn->COLTYPE;
$info->max_length = $rawcolumn->PRECISION;
$info->binary = false;
if (!is_null($rawcolumn->SCALE) && $rawcolumn->SCALE == 0) { // null in oracle scale allows decimals => not integer
// integer
if ($info->name === 'id') {
$info->primary_key = true;
$info->meta_type = 'R';
$info->unique = true;
$info->has_default = false;
} else {
$info->primary_key = false;
$info->meta_type = 'I';
$info->unique = null;
}
$info->scale = 0;
} else {
//float
$info->meta_type = 'N';
$info->primary_key = false;
$info->unsigned = null;
$info->unique = null;
$info->scale = $rawcolumn->SCALE;
}
$info->not_null = ($rawcolumn->NULLS === 'NOT NULL');
$info->has_default = !is_null($rawcolumn->DEFAULTVAL);
if ($info->has_default) {
$info->default_value = trim($rawcolumn->DEFAULTVAL); // remove trailing space
} else {
$info->default_value = null;
}
} else if ($rawcolumn->COLTYPE === 'FLOAT') {
$info->type = $rawcolumn->COLTYPE;
$info->max_length = (int)($rawcolumn->PRECISION * 3.32193);
$info->primary_key = false;
$info->meta_type = 'N';
$info->unique = null;
$info->not_null = ($rawcolumn->NULLS === 'NOT NULL');
$info->has_default = !is_null($rawcolumn->DEFAULTVAL);
if ($info->has_default) {
$info->default_value = trim($rawcolumn->DEFAULTVAL); // remove trailing space
} else {
$info->default_value = null;
}
} else if ($rawcolumn->COLTYPE === 'CLOB'
or $rawcolumn->COLTYPE === 'NCLOB') {
$info->type = $rawcolumn->COLTYPE;
$info->meta_type = 'X';
$info->max_length = -1;
$info->scale = null;
$info->scale = null;
$info->not_null = ($rawcolumn->NULLS === 'NOT NULL');
$info->has_default = !is_null($rawcolumn->DEFAULTVAL);
if ($info->has_default) {
// this is hacky :-(
if ($rawcolumn->DEFAULTVAL === 'NULL') {
$info->default_value = null;
} else if ($rawcolumn->DEFAULTVAL === "' ' ") { // Sometimes it's stored with trailing space
$info->default_value = "";
} else if ($rawcolumn->DEFAULTVAL === "' '") { // Other times it's stored without trailing space
$info->default_value = "";
} else {
$info->default_value = trim($rawcolumn->DEFAULTVAL); // remove trailing space
$info->default_value = substr($info->default_value, 1, strlen($info->default_value)-2); //trim ''
}
} else {
$info->default_value = null;
}
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->unique = null;
} else if ($rawcolumn->COLTYPE === 'BLOB') {
$info->type = $rawcolumn->COLTYPE;
$info->meta_type = 'B';
$info->max_length = -1;
$info->scale = null;
$info->scale = null;
$info->not_null = ($rawcolumn->NULLS === 'NOT NULL');
$info->has_default = !is_null($rawcolumn->DEFAULTVAL);
if ($info->has_default) {
// this is hacky :-(
if ($rawcolumn->DEFAULTVAL === 'NULL') {
$info->default_value = null;
} else if ($rawcolumn->DEFAULTVAL === "' ' ") { // Sometimes it's stored with trailing space
$info->default_value = "";
} else if ($rawcolumn->DEFAULTVAL === "' '") { // Sometimes it's stored without trailing space
$info->default_value = "";
} else {
$info->default_value = trim($rawcolumn->DEFAULTVAL); // remove trailing space
$info->default_value = substr($info->default_value, 1, strlen($info->default_value)-2); //trim ''
}
} else {
$info->default_value = null;
}
$info->primary_key = false;
$info->binary = true;
$info->unsigned = null;
$info->unique = null;
} else {
// unknown type - sorry
$info->type = $rawcolumn->COLTYPE;
$info->meta_type = '?';
}
$structure[$info->name] = new database_column_info($info);
}
return $structure;
}
/**
* Normalise values based in RDBMS dependencies (booleans, LOBs...)
*
* @param database_column_info $column column metadata corresponding with the value we are going to normalise
* @param mixed $value value we are going to normalise
* @return mixed the normalised value
*/
protected function normalise_value($column, $value) {
$this->detect_objects($value);
if (is_bool($value)) { // Always, convert boolean to int
$value = (int)$value;
} else if ($column->meta_type == 'B') { // BLOB detected, we return 'blob' array instead of raw value to allow
if (!is_null($value)) { // binding/executing code later to know about its nature
$value = array('blob' => $value);
}
} else if ($column->meta_type == 'X' && strlen($value) > 4000) { // CLOB detected (>4000 optimisation), we return 'clob'
if (!is_null($value)) { // array instead of raw value to allow binding/
$value = array('clob' => (string)$value); // executing code later to know about its nature
}
} else if ($value === '') {
if ($column->meta_type == 'I' or $column->meta_type == 'F' or $column->meta_type == 'N') {
$value = 0; // prevent '' problems in numeric fields
}
}
return $value;
}
/**
* Transforms the sql and params in order to emulate the LIMIT clause available in other DBs
*
* @param string $sql the SQL select query to execute.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array with the transformed sql and params updated
*/
private function get_limit_sql($sql, array $params = null, $limitfrom=0, $limitnum=0) {
list($limitfrom, $limitnum) = $this->normalise_limit_from_num($limitfrom, $limitnum);
// TODO: Add the /*+ FIRST_ROWS */ hint if there isn't another hint
if ($limitfrom and $limitnum) {
$sql = "SELECT oracle_o.*
FROM (SELECT oracle_i.*, rownum AS oracle_rownum
FROM ($sql) oracle_i
WHERE rownum <= :oracle_num_rows
) oracle_o
WHERE oracle_rownum > :oracle_skip_rows";
$params['oracle_num_rows'] = $limitfrom + $limitnum;
$params['oracle_skip_rows'] = $limitfrom;
} else if ($limitfrom and !$limitnum) {
$sql = "SELECT oracle_o.*
FROM (SELECT oracle_i.*, rownum AS oracle_rownum
FROM ($sql) oracle_i
) oracle_o
WHERE oracle_rownum > :oracle_skip_rows";
$params['oracle_skip_rows'] = $limitfrom;
} else if (!$limitfrom and $limitnum) {
$sql = "SELECT *
FROM ($sql)
WHERE rownum <= :oracle_num_rows";
$params['oracle_num_rows'] = $limitnum;
}
return array($sql, $params);
}
/**
* This function will handle all the column values before being inserted/updated to DB for Oracle
* installations. This is because the "special feature" of Oracle where the empty string is
* equal to NULL and this presents a problem with all our currently NOT NULL default '' fields.
* (and with empties handling in general)
*
* Note that this function is 100% private and should be used, exclusively by DML functions
* in this file. Also, this is considered a DIRTY HACK to be removed when possible.
*
* This function is private and must not be used outside this driver at all
*
* @param $table string the table where the record is going to be inserted/updated (without prefix)
* @param $field string the field where the record is going to be inserted/updated
* @param $value mixed the value to be inserted/updated
*/
private function oracle_dirty_hack ($table, $field, $value) {
// General bound parameter, just hack the spaces and pray it will work.
if (!$table) {
if ($value === '') {
return ' ';
} else if (is_bool($value)) {
return (int)$value;
} else {
return $value;
}
}
// Get metadata
$columns = $this->get_columns($table);
if (!isset($columns[$field])) {
if ($value === '') {
return ' ';
} else if (is_bool($value)) {
return (int)$value;
} else {
return $value;
}
}
$column = $columns[$field];
// !! This paragraph explains behaviour before Moodle 2.0:
//
// For Oracle DB, empty strings are converted to NULLs in DB
// and this breaks a lot of NOT NULL columns currently Moodle. In the future it's
// planned to move some of them to NULL, if they must accept empty values and this
// piece of code will become less and less used. But, for now, we need it.
// What we are going to do is to examine all the data being inserted and if it's
// an empty string (NULL for Oracle) and the field is defined as NOT NULL, we'll modify
// such data in the best form possible ("0" for booleans and numbers and " " for the
// rest of strings. It isn't optimal, but the only way to do so.
// In the opposite, when retrieving records from Oracle, we'll decode " " back to
// empty strings to allow everything to work properly. DIRTY HACK.
// !! These paragraphs explain the rationale about the change for Moodle 2.5:
//
// Before Moodle 2.0, we only used to apply this DIRTY HACK to NOT NULL columns, as
// stated above, but it causes one problem in NULL columns where both empty strings
// and real NULLs are stored as NULLs, being impossible to differentiate them when
// being retrieved from DB.
//
// So, starting with Moodle 2.0, we are going to apply the DIRTY HACK to all the
// CHAR/CLOB columns no matter of their nullability. That way, when retrieving
// NULLABLE fields we'll get proper empties and NULLs differentiated, so we'll be able
// to rely in NULL/empty/content contents without problems, until now that wasn't
// possible at all.
//
// One space DIRTY HACK is now applied automatically for all query parameters
// and results. The only problem is string concatenation where the glue must
// be specified as "' '" sql fragment.
//
// !! Conclusions:
//
// From Moodle 2.5 onwards, ALL empty strings in Oracle DBs will be stored as
// 1-whitespace char, ALL NULLs as NULLs and, obviously, content as content. And
// those 1-whitespace chars will be converted back to empty strings by all the
// get_field/record/set() functions transparently and any SQL needing direct handling
// of empties will have to use placeholders or sql_isempty() helper function.
// If the field isn't VARCHAR or CLOB, skip
if ($column->meta_type != 'C' and $column->meta_type != 'X') {
return $value;
}
// If the value isn't empty, skip
if (!empty($value)) {
return $value;
}
// Now, we have one empty value, going to be inserted to one VARCHAR2 or CLOB field
// Try to get the best value to be inserted
// The '0' string doesn't need any transformation, skip
if ($value === '0') {
return $value;
}
// Transformations start
if (gettype($value) == 'boolean') {
return '0'; // Transform false to '0' that evaluates the same for PHP
} else if (gettype($value) == 'integer') {
return '0'; // Transform 0 to '0' that evaluates the same for PHP
} else if ($value === '') {
return ' '; // Transform '' to ' ' that DON'T EVALUATE THE SAME
// (we'll transform back again on get_records_XXX functions and others)!!
}
// Fail safe to original value
return $value;
}
/**
* Helper function to order by string length desc
*
* @param $a string first element to compare
* @param $b string second element to compare
* @return int < 0 $a goes first (is less), 0 $b goes first, 0 doesn't matter
*/
private function compare_by_length_desc($a, $b) {
return strlen($b) - strlen($a);
}
/**
* Is db in unicode mode?
* @return bool
*/
public function setup_is_unicodedb() {
$sql = "SELECT VALUE
FROM NLS_DATABASE_PARAMETERS
WHERE PARAMETER = 'NLS_CHARACTERSET'";
$this->query_start($sql, null, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_COLUMN);
oci_free_statement($stmt);
return (isset($records['VALUE'][0]) and $records['VALUE'][0] === 'AL32UTF8');
}
/**
* Do NOT use in code, to be used by database_manager only!
* @param string|array $sql query
* @param array|null $tablenames an array of xmldb table names affected by this request.
* @return bool true
* @throws ddl_change_structure_exception A DDL specific exception is thrown for any errors.
*/
public function change_database_structure($sql, $tablenames = null) {
$this->get_manager(); // Includes DDL exceptions classes ;-)
$sqls = (array)$sql;
try {
foreach ($sqls as $sql) {
$this->query_start($sql, null, SQL_QUERY_STRUCTURE);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
}
} catch (ddl_change_structure_exception $e) {
$this->reset_caches($tablenames);
throw $e;
}
$this->reset_caches($tablenames);
return true;
}
protected function bind_params($stmt, array &$params=null, $tablename=null, array &$descriptors = null) {
if ($params) {
$columns = array();
if ($tablename) {
$columns = $this->get_columns($tablename);
}
foreach($params as $key => $value) {
// Decouple column name and param name as far as sometimes they aren't the same
if ($key == 'o_newfieldtoset') { // found case where column and key diverge, handle that
$columnname = key($value); // columnname is the key of the array
$params[$key] = $value[$columnname]; // set the proper value in the $params array and
$value = $value[$columnname]; // set the proper value in the $value variable
} else {
$columnname = preg_replace('/^o_/', '', $key); // Default columnname (for DB introspecting is key), but...
}
// Continue processing
// Now, handle already detected LOBs
if (is_array($value)) { // Let's go to bind special cases (lob descriptors)
if (isset($value['clob'])) {
$lob = oci_new_descriptor($this->oci, OCI_DTYPE_LOB);
if ($descriptors === null) {
throw new coding_exception('moodle_database::bind_params() $descriptors not specified for clob');
}
$descriptors[] = $lob;
oci_bind_by_name($stmt, $key, $lob, -1, SQLT_CLOB);
$lob->writeTemporary($this->oracle_dirty_hack($tablename, $columnname, $params[$key]['clob']), OCI_TEMP_CLOB);
continue; // Column binding finished, go to next one
} else if (isset($value['blob'])) {
$lob = oci_new_descriptor($this->oci, OCI_DTYPE_LOB);
if ($descriptors === null) {
throw new coding_exception('moodle_database::bind_params() $descriptors not specified for clob');
}
$descriptors[] = $lob;
oci_bind_by_name($stmt, $key, $lob, -1, SQLT_BLOB);
$lob->writeTemporary($params[$key]['blob'], OCI_TEMP_BLOB);
continue; // Column binding finished, go to next one
}
} else {
// If, at this point, the param value > 4000 (bytes), let's assume it's a clob
// passed in an arbitrary sql (not processed by normalise_value() ever,
// and let's handle it as such. This will provide proper binding of CLOBs in
// conditions and other raw SQLs not covered by the above function.
if (strlen($value) > 4000) {
$lob = oci_new_descriptor($this->oci, OCI_DTYPE_LOB);
if ($descriptors === null) {
throw new coding_exception('moodle_database::bind_params() $descriptors not specified for clob');
}
$descriptors[] = $lob;
oci_bind_by_name($stmt, $key, $lob, -1, SQLT_CLOB);
$lob->writeTemporary($this->oracle_dirty_hack($tablename, $columnname, $params[$key]), OCI_TEMP_CLOB);
continue; // Param binding finished, go to next one.
}
}
// TODO: Put proper types and length is possible (enormous speedup)
// Arrived here, continue with standard processing, using metadata if possible
if (isset($columns[$columnname])) {
$type = $columns[$columnname]->meta_type;
$maxlength = $columns[$columnname]->max_length;
} else {
$type = '?';
$maxlength = -1;
}
switch ($type) {
case 'I':
case 'R':
// TODO: Optimise
oci_bind_by_name($stmt, $key, $params[$key]);
break;
case 'N':
case 'F':
// TODO: Optimise
oci_bind_by_name($stmt, $key, $params[$key]);
break;
case 'B':
// TODO: Only arrive here if BLOB is null: Bind if so, else exception!
// don't break here
case 'X':
// TODO: Only arrive here if CLOB is null or <= 4000 cc, else exception
// don't break here
default: // Bind as CHAR (applying dirty hack)
// TODO: Optimise
$params[$key] = $this->oracle_dirty_hack($tablename, $columnname, $params[$key]);
// Because of PHP7 bug (https://bugs.php.net/bug.php?id=72524) it seems that it's
// impossible to bind NULL values in a reliable way, let's use empty string
// instead in the mean time.
if ($params[$key] === null && version_compare(PHP_VERSION, '7.0.0', '>=')) {
$params[$key] = '';
}
oci_bind_by_name($stmt, $key, $params[$key]);
}
}
}
return $descriptors;
}
protected function free_descriptors($descriptors) {
foreach ($descriptors as $descriptor) {
// Because all descriptors used in the driver come from LOB::writeTemporary() calls
// we can safely close them here unconditionally.
$descriptor->close();
// Free resources.
oci_free_descriptor($descriptor);
}
}
/**
* This function is used to convert all the Oracle 1-space defaults to the empty string
* like a really DIRTY HACK to allow it to work better until all those NOT NULL DEFAULT ''
* fields will be out from Moodle.
* @param string the string to be converted to '' (empty string) if it's ' ' (one space)
* @param mixed the key of the array in case we are using this function from array_walk,
* defaults to null for other (direct) uses
* @return boolean always true (the converted variable is returned by reference)
*/
public static function onespace2empty(&$item, $key=null) {
$item = ($item === ' ') ? '' : $item;
return true;
}
/**
* Execute 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 $params query parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function execute($sql, array $params=null) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
if (strpos($sql, ';') !== false) {
throw new coding_exception('moodle_database::execute() Multiple sql statements found or bound parameters not used properly in query!');
}
list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$stmt = $this->parse_query($sql);
$descriptors = array();
$this->bind_params($stmt, $params, null, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
return true;
}
/**
* Get a single database record as an object using a SQL statement.
*
* The SQL statement should normally only return one record.
* It is recommended to use get_records_sql() if more matches possible!
*
* @param string $sql The SQL string you wish to be executed, should normally only return one record.
* @param array $params array of sql parameters
* @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
* IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
* MUST_EXIST means throw exception if no record or multiple records found
* @return mixed a fieldset object containing the first matching record, false or exception if error not found depending on mode
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_record_sql($sql, array $params=null, $strictness=IGNORE_MISSING) {
$strictness = (int)$strictness;
if ($strictness == IGNORE_MULTIPLE) {
// do not limit here - ORA does not like that
$rs = $this->get_recordset_sql($sql, $params);
$result = false;
foreach ($rs as $rec) {
$result = $rec;
break;
}
$rs->close();
return $result;
}
return parent::get_record_sql($sql, $params, $strictness);
}
/**
* Get a number of records as a moodle_recordset using a SQL statement.
*
* 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_sql - it leads to simpler code.
*
* The return type is like:
* @see function get_recordset.
*
* @param string $sql the SQL select query to execute.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return moodle_recordset instance
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
list($rawsql, $params) = $this->get_limit_sql($sql, $params, $limitfrom, $limitnum);
list($rawsql, $params) = $this->tweak_param_names($rawsql, $params);
$this->query_start($rawsql, $params, SQL_QUERY_SELECT);
$stmt = $this->parse_query($rawsql);
$descriptors = array();
$this->bind_params($stmt, $params, null, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
return $this->create_recordset($stmt);
}
protected function create_recordset($stmt) {
return new oci_native_moodle_recordset($stmt);
}
/**
* Get a number of records as an array of objects using a SQL statement.
*
* Return value is like:
* @see function get_records.
*
* @param string $sql the SQL select query to execute. The first column of this SELECT statement
* must be a unique value (usually the 'id' field), as it will be used as the key of the
* returned array.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array of objects, or empty array if no records were found
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
list($rawsql, $params) = $this->get_limit_sql($sql, $params, $limitfrom, $limitnum);
list($rawsql, $params) = $this->tweak_param_names($rawsql, $params);
$this->query_start($rawsql, $params, SQL_QUERY_SELECT);
$stmt = $this->parse_query($rawsql);
$descriptors = array();
$this->bind_params($stmt, $params, null, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_ROW);
oci_free_statement($stmt);
$return = array();
foreach ($records as $row) {
$row = array_change_key_case($row, CASE_LOWER);
unset($row['oracle_rownum']);
array_walk($row, array('oci_native_moodle_database', 'onespace2empty'));
$id = reset($row);
if (isset($return[$id])) {
$colname = key($row);
debugging("Did you remember to make the first column something unique in your call to get_records? Duplicate value '$id' found in column '$colname'.", DEBUG_DEVELOPER);
}
$return[$id] = (object)$row;
}
return $return;
}
/**
* Selects records and return values (first field) as an array using a SQL statement.
*
* @param string $sql The SQL query
* @param array $params array of sql parameters
* @return array of values
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_fieldset_sql($sql, array $params=null) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_SELECT);
$stmt = $this->parse_query($sql);
$descriptors = array();
$this->bind_params($stmt, $params, null, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_COLUMN);
oci_free_statement($stmt);
$return = reset($records);
array_walk($return, array('oci_native_moodle_database', 'onespace2empty'));
return $return;
}
/**
* Insert new record into database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool $returnit return it of inserted record
* @param bool $bulk true means repeated inserts expected
* @param bool $customsequence true if 'id' included in $params, disables $returnid
* @return bool|int true or new id
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function insert_record_raw($table, $params, $returnid=true, $bulk=false, $customsequence=false) {
if (!is_array($params)) {
$params = (array)$params;
}
$returning = "";
if ($customsequence) {
if (!isset($params['id'])) {
throw new coding_exception('moodle_database::insert_record_raw() id field must be specified if custom sequences used.');
}
$returnid = false;
} else {
unset($params['id']);
if ($returnid) {
$returning = " RETURNING id INTO :oracle_id"; // crazy name nobody is ever going to use or parameter ;-)
}
}
if (empty($params)) {
throw new coding_exception('moodle_database::insert_record_raw() no fields found.');
}
$fields = implode(',', array_keys($params));
$values = array();
foreach ($params as $pname => $value) {
$values[] = ":$pname";
}
$values = implode(',', $values);
$sql = "INSERT INTO {" . $table . "} ($fields) VALUES ($values)";
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$sql .= $returning;
$id = 0;
// note we don't need tweak_param_names() here. Placeholders are safe column names. MDL-28080
// list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_INSERT);
$stmt = $this->parse_query($sql);
if ($returning) {
oci_bind_by_name($stmt, ":oracle_id", $id, 10, SQLT_INT);
}
$descriptors = array();
$this->bind_params($stmt, $params, $table, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
if (!$returnid) {
return true;
}
if (!$returning) {
die('TODO - implement oracle 9.2 insert support'); //TODO
}
return (int)$id;
}
/**
* Insert a record into a table and return the "id" field if required.
*
* Some conversions and safety checks are carried out. Lobs are supported.
* If the return ID isn't required, then this just reports success as true/false.
* $data is an object containing needed data
* @param string $table The database table to be inserted into
* @param object $data A data object with values for one or more fields in the record
* @param bool $returnid Should the id of the newly created record entry be returned? If this option is not requested then true/false is returned.
* @return bool|int true or new id
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function insert_record($table, $dataobject, $returnid=true, $bulk=false) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
if (empty($columns)) {
throw new dml_exception('ddltablenotexist', $table);
}
$cleaned = array();
foreach ($dataobject as $field=>$value) {
if ($field === 'id') {
continue;
}
if (!isset($columns[$field])) { // Non-existing table field, skip it
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
return $this->insert_record_raw($table, $cleaned, $returnid, $bulk);
}
/**
* Import a record into a table, id field is required.
* Safety checks are NOT carried out. Lobs are supported.
*
* @param string $table name of database table to be inserted into
* @param object $dataobject A data object with values for one or more fields in the record
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function import_record($table, $dataobject) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
$cleaned = array();
foreach ($dataobject as $field=>$value) {
if (!isset($columns[$field])) {
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
return $this->insert_record_raw($table, $cleaned, false, true, true);
}
/**
* Update record in database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function update_record_raw($table, $params, $bulk=false) {
$params = (array)$params;
if (!isset($params['id'])) {
throw new coding_exception('moodle_database::update_record_raw() id field must be specified.');
}
if (empty($params)) {
throw new coding_exception('moodle_database::update_record_raw() no fields found.');
}
$sets = array();
foreach ($params as $field=>$value) {
if ($field == 'id') {
continue;
}
$sets[] = "$field = :$field";
}
$sets = implode(',', $sets);
$sql = "UPDATE {" . $table . "} SET $sets WHERE id=:id";
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
// note we don't need tweak_param_names() here. Placeholders are safe column names. MDL-28080
// list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$stmt = $this->parse_query($sql);
$descriptors = array();
$this->bind_params($stmt, $params, $table, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
return true;
}
/**
* Update a record in a table
*
* $dataobject is an object containing needed data
* Relies on $dataobject having a variable "id" to
* specify the record to update
*
* @param string $table The database table to be checked against.
* @param object $dataobject An object with contents equal to fieldname=>fieldvalue. Must have an entry for 'id' to map to the table specified.
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function update_record($table, $dataobject, $bulk=false) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
$cleaned = array();
foreach ($dataobject as $field=>$value) {
if (!isset($columns[$field])) {
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
$this->update_record_raw($table, $cleaned, $bulk);
return true;
}
/**
* Set a single field in every table record which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $newfield the field to set.
* @param string $newvalue the value to set the field to.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function set_field_select($table, $newfield, $newvalue, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
if (is_null($params)) {
$params = array();
}
// Get column metadata
$columns = $this->get_columns($table);
$column = $columns[$newfield];
$newvalue = $this->normalise_value($column, $newvalue);
list($select, $params, $type) = $this->fix_sql_params($select, $params);
if (is_bool($newvalue)) {
$newvalue = (int)$newvalue; // prevent "false" problems
}
if (is_null($newvalue)) {
$newsql = "$newfield = NULL";
} else {
// Set the param to array ($newfield => $newvalue) and key to 'newfieldtoset'
// name in the build sql. Later, bind_params() will detect the value array and
// perform the needed modifications to allow the query to work. Note that
// 'newfieldtoset' is one arbitrary name that hopefully won't be used ever
// in order to avoid problems where the same field is used both in the set clause and in
// the conditions. This was breaking badly in drivers using NAMED params like oci.
$params['newfieldtoset'] = array($newfield => $newvalue);
$newsql = "$newfield = :newfieldtoset";
}
$sql = "UPDATE {" . $table . "} SET $newsql $select";
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$stmt = $this->parse_query($sql);
$descriptors = array();
$this->bind_params($stmt, $params, $table, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
return true;
}
/**
* Delete one or more records from a table which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call (used to define the selection criteria).
* @param array $params array of sql parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function delete_records_select($table, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
$sql = "DELETE FROM {" . $table . "} $select";
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
list($sql, $params) = $this->tweak_param_names($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$stmt = $this->parse_query($sql);
$descriptors = array();
$this->bind_params($stmt, $params, null, $descriptors);
$result = oci_execute($stmt, $this->commit_status);
$this->free_descriptors($descriptors);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
return true;
}
function sql_null_from_clause() {
return ' FROM dual';
}
public function sql_bitand($int1, $int2) {
return 'bitand((' . $int1 . '), (' . $int2 . '))';
}
public function sql_bitnot($int1) {
return '((0 - (' . $int1 . ')) - 1)';
}
public function sql_bitor($int1, $int2) {
return 'MOODLELIB.BITOR(' . $int1 . ', ' . $int2 . ')';
}
public function sql_bitxor($int1, $int2) {
return 'MOODLELIB.BITXOR(' . $int1 . ', ' . $int2 . ')';
}
/**
* Returns the SQL text to be used in order to perform module '%'
* operation - remainder after division
*
* @param integer int1 first integer in the operation
* @param integer int2 second integer in the operation
* @return string the piece of SQL code to be used in your statement.
*/
public function sql_modulo($int1, $int2) {
return 'MOD(' . $int1 . ', ' . $int2 . ')';
}
public function sql_cast_char2int($fieldname, $text=false) {
if (!$text) {
return ' CAST(' . $fieldname . ' AS INT) ';
} else {
return ' CAST(' . $this->sql_compare_text($fieldname) . ' AS INT) ';
}
}
public function sql_cast_char2real($fieldname, $text=false) {
if (!$text) {
return ' CAST(' . $fieldname . ' AS FLOAT) ';
} else {
return ' CAST(' . $this->sql_compare_text($fieldname) . ' AS FLOAT) ';
}
}
/**
* Returns 'LIKE' part of a query.
*
* @param string $fieldname usually name of the table column
* @param string $param usually bound query parameter (?, :named)
* @param bool $casesensitive use case sensitive search
* @param bool $accensensitive use accent sensitive search (not all databases support accent insensitive)
* @param bool $notlike true means "NOT LIKE"
* @param string $escapechar escape char for '%' and '_'
* @return string SQL code fragment
*/
public function sql_like($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notlike = false, $escapechar = '\\') {
if (strpos($param, '%') !== false) {
debugging('Potential SQL injection detected, sql_like() expects bound parameters (? or :named)');
}
$LIKE = $notlike ? 'NOT LIKE' : 'LIKE';
// no accent sensitiveness here for now, sorry
if ($casesensitive) {
return "$fieldname $LIKE $param ESCAPE '$escapechar'";
} else {
return "LOWER($fieldname) $LIKE LOWER($param) ESCAPE '$escapechar'";
}
}
public function sql_concat() {
$arr = func_get_args();
if (empty($arr)) {
return " ' ' ";
}
foreach ($arr as $k => $v) {
if ($v === "' '") {
$arr[$k] = "'*OCISP*'"; // New mega hack.
}
}
$s = $this->recursive_concat($arr);
return " MOODLELIB.UNDO_MEGA_HACK($s) ";
}
public function sql_concat_join($separator="' '", $elements = array()) {
if ($separator === "' '") {
$separator = "'*OCISP*'"; // New mega hack.
}
foreach ($elements as $k => $v) {
if ($v === "' '") {
$elements[$k] = "'*OCISP*'"; // New mega hack.
}
}
for ($n = count($elements)-1; $n > 0 ; $n--) {
array_splice($elements, $n, 0, $separator);
}
if (empty($elements)) {
return " ' ' ";
}
$s = $this->recursive_concat($elements);
return " MOODLELIB.UNDO_MEGA_HACK($s) ";
}
/**
* Constructs 'IN()' or '=' sql fragment
*
* Method overriding {@link moodle_database::get_in_or_equal} to be able to get
* more than 1000 elements working, to avoid ORA-01795. We use a pivoting technique
* to be able to transform the params into virtual rows, so the original IN()
* expression gets transformed into a subquery. Once more, be noted that we shouldn't
* be using ever get_in_or_equal() with such number of parameters (proper subquery and/or
* chunking should be used instead).
*
* @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, $onemptyitems=false) {
list($sql, $params) = parent::get_in_or_equal($items, $type, $prefix, $equal, $onemptyitems);
// Less than 1000 elements, nothing to do.
if (count($params) < 1000) {
return array($sql, $params); // Return unmodified.
}
// Extract the interesting parts of the sql to rewrite.
if (preg_match('!(^.*IN \()([^\)]*)(.*)$!', $sql, $matches) === false) {
return array($sql, $params); // Return unmodified.
}
$instart = $matches[1];
$insql = $matches[2];
$inend = $matches[3];
$newsql = '';
// Some basic verification about the matching going ok.
$insqlarr = explode(',', $insql);
if (count($insqlarr) !== count($params)) {
return array($sql, $params); // Return unmodified.
}
// Arrived here, we need to chunk and pivot the params, building a new sql (params remain the same).
$addunionclause = false;
while ($chunk = array_splice($insqlarr, 0, 125)) { // Each chunk will handle up to 125 (+125 +1) elements (DECODE max is 255).
$chunksize = count($chunk);
if ($addunionclause) {
$newsql .= "\n UNION ALL";
}
$newsql .= "\n SELECT DECODE(pivot";
$counter = 1;
foreach ($chunk as $element) {
$newsql .= ",\n {$counter}, " . trim($element);
$counter++;
}
$newsql .= ")";
$newsql .= "\n FROM dual";
$newsql .= "\n CROSS JOIN (SELECT LEVEL AS pivot FROM dual CONNECT BY LEVEL <= {$chunksize})";
$addunionclause = true;
}
// Rebuild the complete IN() clause and return it.
return array($instart . $newsql . $inend, $params);
}
/**
* Mega hacky magic to work around crazy Oracle NULL concats.
* @param array $args
* @return string
*/
protected function recursive_concat(array $args) {
$count = count($args);
if ($count == 1) {
$arg = reset($args);
return $arg;
}
if ($count == 2) {
$args[] = "' '";
// No return here intentionally.
}
$first = array_shift($args);
$second = array_shift($args);
$third = $this->recursive_concat($args);
return "MOODLELIB.TRICONCAT($first, $second, $third)";
}
/**
* Returns the SQL for returning searching one string for the location of another.
*/
public function sql_position($needle, $haystack) {
return "INSTR(($haystack), ($needle))";
}
/**
* Returns the SQL to know if one field is empty.
*
* @param string $tablename Name of the table (without prefix). Not used for now but can be
* necessary in the future if we want to use some introspection using
* meta information against the DB.
* @param string $fieldname Name of the field we are going to check
* @param bool $nullablefield For specifying if the field is nullable (true) or no (false) in the DB.
* @param bool $textfield For specifying if it is a text (also called clob) field (true) or a varchar one (false)
* @return string the sql code to be added to check for empty values
*/
public function sql_isempty($tablename, $fieldname, $nullablefield, $textfield) {
if ($textfield) {
return " (".$this->sql_compare_text($fieldname)." = ' ') ";
} else {
return " ($fieldname = ' ') ";
}
}
public function sql_order_by_text($fieldname, $numchars=32) {
return 'dbms_lob.substr(' . $fieldname . ', ' . $numchars . ',1)';
}
/**
* Is the required OCI server package installed?
* @return bool
*/
protected function oci_package_installed() {
$sql = "SELECT 1
FROM user_objects
WHERE object_type = 'PACKAGE BODY'
AND object_name = 'MOODLELIB'
AND status = 'VALID'";
$this->query_start($sql, null, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
$records = null;
oci_fetch_all($stmt, $records, 0, -1, OCI_FETCHSTATEMENT_BY_ROW);
oci_free_statement($stmt);
return isset($records[0]) && reset($records[0]) ? true : false;
}
/**
* Try to add required moodle package into oracle server.
*/
protected function attempt_oci_package_install() {
$sqls = file_get_contents(__DIR__.'/oci_native_moodle_package.sql');
$sqls = preg_split('/^\/$/sm', $sqls);
foreach ($sqls as $sql) {
$sql = trim($sql);
if ($sql === '' or $sql === 'SHOW ERRORS') {
continue;
}
$this->change_database_structure($sql);
}
}
/**
* Does this driver support tool_replace?
*
* @since Moodle 2.8
* @return bool
*/
public function replace_all_text_supported() {
return true;
}
public function session_lock_supported() {
return true;
}
/**
* Obtain session lock
* @param int $rowid id of the row with session record
* @param int $timeout max allowed time to wait for the lock in seconds
* @return void
*/
public function get_session_lock($rowid, $timeout) {
parent::get_session_lock($rowid, $timeout);
$fullname = $this->dbname.'-'.$this->prefix.'-session-'.$rowid;
$sql = 'SELECT MOODLELIB.GET_LOCK(:lockname, :locktimeout) FROM DUAL';
$params = array('lockname' => $fullname , 'locktimeout' => $timeout);
$this->query_start($sql, $params, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$this->bind_params($stmt, $params);
$result = oci_execute($stmt, $this->commit_status);
if ($result === false) { // Any failure in get_lock() raises error, causing return of bool false
throw new dml_sessionwait_exception();
}
$this->query_end($result, $stmt);
oci_free_statement($stmt);
}
public function release_session_lock($rowid) {
if (!$this->used_for_db_sessions) {
return;
}
parent::release_session_lock($rowid);
$fullname = $this->dbname.'-'.$this->prefix.'-session-'.$rowid;
$params = array('lockname' => $fullname);
$sql = 'SELECT MOODLELIB.RELEASE_LOCK(:lockname) FROM DUAL';
$this->query_start($sql, $params, SQL_QUERY_AUX);
$stmt = $this->parse_query($sql);
$this->bind_params($stmt, $params);
$result = oci_execute($stmt, $this->commit_status);
$this->query_end($result, $stmt);
oci_free_statement($stmt);
}
/**
* Driver specific start of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function begin_transaction() {
$this->commit_status = OCI_DEFAULT; //Done! ;-)
}
/**
* Driver specific commit of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function commit_transaction() {
$this->query_start('--oracle_commit', NULL, SQL_QUERY_AUX);
$result = oci_commit($this->oci);
$this->commit_status = OCI_COMMIT_ON_SUCCESS;
$this->query_end($result);
}
/**
* Driver specific abort of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function rollback_transaction() {
$this->query_start('--oracle_rollback', NULL, SQL_QUERY_AUX);
$result = oci_rollback($this->oci);
$this->commit_status = OCI_COMMIT_ON_SUCCESS;
$this->query_end($result);
}
}