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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 2 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 sqlsrv class representing moodle database interface.
*
* @package core
* @subpackage dml
* @copyright 2009 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v2 or later
*/
defined('MOODLE_INTERNAL') || die();
require_once($CFG->libdir.'/dml/moodle_database.php');
require_once($CFG->libdir.'/dml/sqlsrv_native_moodle_recordset.php');
require_once($CFG->libdir.'/dml/sqlsrv_native_moodle_temptables.php');
/**
* Native sqlsrv class representing moodle database interface.
*/
class sqlsrv_native_moodle_database extends moodle_database {
protected $sqlsrv = null;
protected $last_error_reporting; // To handle SQL*Server-Native driver default verbosity
protected $temptables; // Control existing temptables (sqlsrv_moodle_temptables object)
protected $collation; // current DB collation cache
/**
* Constructor - instantiates the database, specifying if it's external (connect to other systems) or no (Moodle DB)
* note this has effect to decide if prefix checks must be performed or no
* @param bool true means external database used
*/
public function __construct($external=false) {
parent::__construct($external);
}
/**
* 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() {
// use 'function_exists()' rather than 'extension_loaded()' because
// the name used by 'extension_loaded()' is case specific! The extension
// therefore *could be* mixed case and hence not found.
if (!function_exists('sqlsrv_num_rows')) {
return get_string('sqlsrvextensionisnotpresentinphp', 'install');
}
return true;
}
/**
* Returns database family type - describes SQL dialect
* Note: can be used before connect()
* @return string db family name (mysql, postgres, mssql, sqlsrv, oracle, etc.)
*/
public function get_dbfamily() {
return 'mssql';
}
/**
* 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 'sqlsrv';
}
/**
* 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('nativesqlsrv', 'install');
}
/**
* Returns localised database configuration help.
* Note: can be used before connect()
* @return string
*/
public function get_configuration_help() {
return get_string('nativesqlsrvhelp', 'install');
}
/**
* Returns localised database description
* Note: can be used before connect()
* @return string
*/
public function get_configuration_hints() {
$str = get_string('databasesettingssub_sqlsrv', 'install');
$str .= "<p style='text-align:right'><a href=\"javascript:void(0)\" ";
$str .= "onclick=\"return window.open('http://docs.moodle.org/en/Installing_sqlsrv_for_PHP')\"";
$str .= ">";
$str .= '<img src="pix/docs.gif'.'" alt="Docs" class="iconhelp" />';
$str .= get_string('moodledocslink', 'install').'</a></p>';
return $str;
}
/**
* Connect to db
* Must be called before other methods.
* @param string $dbhost
* @param string $dbuser
* @param string $dbpass
* @param string $dbname
* @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) {
$driverstatus = $this->driver_installed();
if ($driverstatus !== true) {
throw new dml_exception('dbdriverproblem', $driverstatus);
}
/*
* Log all Errors.
*/
sqlsrv_configure("WarningsReturnAsErrors", FALSE);
sqlsrv_configure("LogSubsystems", SQLSRV_LOG_SYSTEM_ALL);
sqlsrv_configure("LogSeverity", SQLSRV_LOG_SEVERITY_ERROR);
$this->store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, $dboptions);
$this->sqlsrv = sqlsrv_connect($this->dbhost, array
(
'UID' => $this->dbuser,
'PWD' => $this->dbpass,
'Database' => $this->dbname,
'CharacterSet' => 'UTF-8',
'MultipleActiveResultSets' => true,
'ConnectionPooling' => !empty($this->dboptions['dbpersist']),
'ReturnDatesAsStrings' => true,
));
if ($this->sqlsrv === false) {
$this->sqlsrv = null;
$dberr = $this->get_last_error();
throw new dml_connection_exception($dberr);
}
// Allow quoted identifiers
$sql = "SET QUOTED_IDENTIFIER ON";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
// Force ANSI nulls so the NULL check was done by IS NULL and NOT IS NULL
// instead of equal(=) and distinct(<>) symbols
$sql = "SET ANSI_NULLS ON";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
// Force ANSI warnings so arithmetic/string overflows will be
// returning error instead of transparently truncating data
$sql = "SET ANSI_WARNINGS ON";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
// Concatenating null with anything MUST return NULL
$sql = "SET CONCAT_NULL_YIELDS_NULL ON";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
// Set transactions isolation level to READ_COMMITTED
// prevents dirty reads when using transactions +
// is the default isolation level of sqlsrv
$sql = "SET TRANSACTION ISOLATION LEVEL READ COMMITTED";
$this->query_start($sql, NULL, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
// Connection established and configured, going to instantiate the temptables controller
$this->temptables = new sqlsrv_native_moodle_temptables($this);
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 ($this->sqlsrv) {
sqlsrv_close($this->sqlsrv);
$this->sqlsrv = 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, $extrainfo);
}
/**
* Called immediately after each db query.
* @param mixed db specific result
* @return void
*/
protected function query_end($result) {
parent::query_end($result);
}
/**
* Returns database server info array
* @return array
*/
public function get_server_info() {
static $info;
if (!$info) {
$server_info = sqlsrv_server_info($this->sqlsrv);
if ($server_info) {
$info['description'] = $server_info['SQLServerName'];
$info['version'] = $server_info['SQLServerVersion'];
$info['database'] = $server_info['CurrentDatabase'];
}
}
return $info;
}
/**
* Get the minimum SQL allowed
*
* @param mixed $version
* @return mixed
*/
protected function is_min_version($version) {
$server = $this->get_server_info();
$server = $server['version'];
return version_compare($server, $version, '>=');
}
/**
* Override: Converts short table name {tablename} to real table name
* supporting temp tables (#) if detected
*
* @param string sql
* @return string sql
*/
protected function fix_table_names($sql) {
if (preg_match_all('/\{([a-z][a-z0-9_]*)\}/i', $sql, $matches)) {
foreach ($matches[0] as $key => $match) {
$name = $matches[1][$key];
if ($this->temptables->is_temptable($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
*/
protected function allowed_param_types() {
return SQL_PARAMS_QM; // sqlsrv 1.1 can bind
}
/**
* Returns last error reported by database engine.
* @return string error message
*/
public function get_last_error() {
$retErrors = sqlsrv_errors(SQLSRV_ERR_ALL);
$errorMessage = 'No errors found';
if ($retErrors != null) {
$errorMessage = '';
foreach ($retErrors as $arrError) {
$errorMessage .= "SQLState: ".$arrError['SQLSTATE']."<br>\n";
$errorMessage .= "Error Code: ".$arrError['code']."<br>\n";
$errorMessage .= "Message: ".$arrError['message']."<br>\n";
}
}
return $errorMessage;
}
/***
* Bound variables *are* supported. Until I can get it to work, emulate the bindings
* The challenge/problem/bug is that although they work, doing a SELECT SCOPE_IDENTITY()
* doesn't return a value (no result set)
*/
/**
* Prepare the query binding and do the actual query.
*
* @param string $sql The sql statement
* @param mixed $params array of params for binding. If NULL, they are ignored.
* @param mixed $sql_query_type - Type of operation
* @param mixed $free_result - Default true, transaction query will be freed.
*/
private function do_query($sql, $params, $sql_query_type, $free_result = true) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$sql = $this->emulate_bound_params($sql, $params);
$this->query_start($sql, $params, $sql_query_type);
$result = sqlsrv_query($this->sqlsrv, $sql);
if ($result === false) {
// TODO do something with error or just use if DEV or DEBUG?
$dberr = $this->get_last_error();
}
$this->query_end($result);
if ($free_result) {
$this->free_result($result);
return true;
}
return $result;
}
/**
* Return tables in database WITHOUT current prefix
* @return array of table names in lowercase and without prefix
*/
public function get_tables($usecache = true) {
if ($usecache and count($this->tables) > 0) {
return $this->tables;
}
$this->tables = array ();
$prefix = str_replace('_', '\\_', $this->prefix);
$sql = "SELECT table_name
FROM information_schema.tables
WHERE table_name LIKE '$prefix%' ESCAPE '\\' AND table_type = 'BASE TABLE'";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
if ($result) {
while ($row = sqlsrv_fetch_array($result)) {
$tablename = reset($row);
if (strpos($tablename, $this->prefix) !== 0) {
continue;
}
$tablename = substr($tablename, strlen($this->prefix));
$this->tables[$tablename] = $tablename;
}
$this->free_result($result);
}
// Add the currently available temptables
$this->tables = array_merge($this->tables, $this->temptables->get_temptables());
return $this->tables;
}
/**
* Return table indexes - everything lowercased
* @return array of arrays
*/
public function get_indexes($table) {
$indexes = array ();
$tablename = $this->prefix.$table;
// Indexes aren't covered by information_schema metatables, so we need to
// go to sys ones. Skipping primary key indexes on purpose.
$sql = "SELECT i.name AS index_name, i.is_unique, ic.index_column_id, c.name AS column_name
FROM sys.indexes i
JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id
JOIN sys.tables t ON i.object_id = t.object_id
WHERE t.name = '$tablename' AND i.is_primary_key = 0
ORDER BY i.name, i.index_id, ic.index_column_id";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
if ($result) {
$lastindex = '';
$unique = false;
$columns = array ();
while ($row = sqlsrv_fetch_array($result, SQLSRV_FETCH_ASSOC)) {
if ($lastindex and $lastindex != $row['index_name'])
{ // Save lastindex to $indexes and reset info
$indexes[$lastindex] = array
(
'unique' => $unique,
'columns' => $columns
);
$unique = false;
$columns = array ();
}
$lastindex = $row['index_name'];
$unique = empty($row['is_unique']) ? false : true;
$columns[] = $row['column_name'];
}
if ($lastindex) { // Add the last one if exists
$indexes[$lastindex] = array
(
'unique' => $unique,
'columns' => $columns
);
}
$this->free_result($result);
}
return $indexes;
}
/**
* Returns detailed information about columns in table. This information is cached internally.
* @param string $table name
* @param bool $usecache
* @return array array of database_column_info objects indexed with column names
*/
public function get_columns($table, $usecache = true) {
if ($usecache and isset($this->columns[$table])) {
return $this->columns[$table];
}
$this->columns[$table] = array ();
if (!$this->temptables->is_temptable($table)) { // normal table, get metadata from own schema
$sql = "SELECT column_name AS name,
data_type AS type,
numeric_precision AS max_length,
character_maximum_length AS char_max_length,
numeric_scale AS scale,
is_nullable AS is_nullable,
columnproperty(object_id(quotename(table_schema) + '.' + quotename(table_name)), column_name, 'IsIdentity') AS auto_increment,
column_default AS default_value
FROM information_schema.columns
WHERE table_name = '{".$table."}'
ORDER BY ordinal_position";
} else { // temp table, get metadata from tempdb schema
$sql = "SELECT column_name AS name,
data_type AS type,
numeric_precision AS max_length,
character_maximum_length AS char_max_length,
numeric_scale AS scale,
is_nullable AS is_nullable,
columnproperty(object_id(quotename(table_schema) + '.' + quotename(table_name)), column_name, 'IsIdentity') AS auto_increment,
column_default AS default_value
FROM tempdb.information_schema.columns ".
// check this statement
// JOIN tempdb..sysobjects ON name = table_name
// WHERE id = object_id('tempdb..{".$table."}')
"WHERE table_name LIKE '{".$table."}__________%'
ORDER BY ordinal_position";
}
list($sql, $params, $type) = $this->fix_sql_params($sql, null);
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
if (!$result) {
return array ();
}
while ($rawcolumn = sqlsrv_fetch_array($result, SQLSRV_FETCH_ASSOC)) {
$rawcolumn = (object)$rawcolumn;
$info = new stdClass();
$info->name = $rawcolumn->name;
$info->type = $rawcolumn->type;
$info->meta_type = $this->sqlsrvtype2moodletype($info->type);
// Prepare auto_increment info
$info->auto_increment = $rawcolumn->auto_increment ? true : false;
// Define type for auto_increment columns
$info->meta_type = ($info->auto_increment && $info->meta_type == 'I') ? 'R' : $info->meta_type;
// id columns being auto_incremnt are PK by definition
$info->primary_key = ($info->name == 'id' && $info->meta_type == 'R' && $info->auto_increment);
// Put correct length for character and LOB types
$info->max_length = $info->meta_type == 'C' ? $rawcolumn->char_max_length : $rawcolumn->max_length;
$info->max_length = ($info->meta_type == 'X' || $info->meta_type == 'B') ? -1 : $info->max_length;
// Scale
$info->scale = $rawcolumn->scale ? $rawcolumn->scale : false;
// Prepare not_null info
$info->not_null = $rawcolumn->is_nullable == 'NO' ? true : false;
// Process defaults
$info->has_default = !empty($rawcolumn->default_value);
if ($rawcolumn->default_value === NULL) {
$info->default_value = NULL;
} else {
$info->default_value = preg_replace("/^[\(N]+[']?(.*?)[']?[\)]+$/", '\\1', $rawcolumn->default_value);
}
// Process binary
$info->binary = $info->meta_type == 'B' ? true : false;
$this->columns[$table][$info->name] = new database_column_info($info);
}
$this->free_result($result);
return $this->columns[$table];
}
/**
* 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, $value) {
if (is_bool($value)) { /// Always, convert boolean to int
$value = (int)$value;
} // And continue processing because text columns with numeric info need special handling below
if ($column->meta_type == 'B')
{ // BLOBs need to be properly "packed", but can be inserted directly if so.
if (!is_null($value)) { // If value not null, unpack it to unquoted hexadecimal byte-string format
$value = unpack('H*hex', $value); // we leave it as array, so emulate_bound_params() can detect it
} // easily and "bind" the param ok.
} else if ($column->meta_type == 'X') { // sqlsrv doesn't cast from int to text, so if text column
if (is_numeric($value)) { // and is numeric value then cast to string
$value = array('numstr' => (string)$value); // and put into array, so emulate_bound_params() will know how
} // to "bind" the param ok, avoiding reverse conversion to number
} 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;
}
/**
* Selectively call sqlsrv_free_stmt(), avoiding some warnings without using the horrible @
*
* @param sqlsrv_resource $resource resource to be freed if possible
*/
private function free_result($resource) {
if (!is_bool($resource)) { // true/false resources cannot be freed
return sqlsrv_free_stmt($resource);
}
}
/**
* Provides mapping between sqlsrv native data types and moodle_database - database_column_info - ones)
*
* @param string $sqlsrv_type native sqlsrv data type
* @return string 1-char database_column_info data type
*/
private function sqlsrvtype2moodletype($sqlsrv_type) {
$type = null;
switch (strtoupper($sqlsrv_type)) {
case 'BIT':
$type = 'L';
break;
case 'INT':
case 'SMALLINT':
case 'INTEGER':
case 'BIGINT':
$type = 'I';
break;
case 'DECIMAL':
case 'REAL':
case 'FLOAT':
$type = 'N';
break;
case 'VARCHAR':
case 'NVARCHAR':
$type = 'C';
break;
case 'TEXT':
case 'NTEXT':
case 'VARCHAR(MAX)':
case 'NVARCHAR(MAX)':
$type = 'X';
break;
case 'IMAGE':
case 'VARBINARY(MAX)':
$type = 'B';
break;
case 'DATETIME':
$type = 'D';
break;
}
if (!$type) {
throw new dml_exception('invalidsqlsrvnativetype', $sqlsrv_type);
}
return $type;
}
/**
* Do NOT use in code, to be used by database_manager only!
* @param string $sql query
* @return bool true
* @throws dml_exception if error
*/
public function change_database_structure($sql) {
$this->reset_caches();
$this->query_start($sql, null, SQL_QUERY_STRUCTURE);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
return true;
}
/**
* Prepare the array of params for native binding
*/
protected function build_native_bound_params(array $params = null) {
return null;
}
/**
* Workaround for SQL*Server Native driver similar to MSSQL driver for
* consistent behavior.
*/
protected function emulate_bound_params($sql, array $params = null) {
if (empty($params)) {
return $sql;
}
/// ok, we have verified sql statement with ? and correct number of params
$return = strtok($sql, '?');
foreach ($params as $param) {
if (is_bool($param)) {
$return .= (int)$param;
} else if (is_array($param) && isset($param['hex'])) { // detect hex binary, bind it specially
$return .= '0x'.$param['hex'];
} else if (is_array($param) && isset($param['numstr'])) { // detect numerical strings that *must not*
$return .= "N'{$param['numstr']}'"; // be converted back to number params, but bound as strings
} else if (is_null($param)) {
$return .= 'NULL';
} else if (is_number($param)) { // we can not use is_numeric() because it eats leading zeros from strings like 0045646
$return .= "'$param'"; // this is a hack for MDL-23997, we intentionally use string because it is compatible with both nvarchar and int types
} else if (is_float($param)) {
$return .= $param;
} else {
$param = str_replace("'", "''", $param);
$return .= "N'$param'";
}
$return .= strtok('?');
}
return $return;
}
/**
* 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::execute_sql() instead!
* @param string $sql query
* @param array $params query parameters
* @return bool true
* @throws dml_exception if error
*/
public function execute($sql, array $params = null) {
if (strpos($sql, ';') !== false) {
throw new coding_exception('moodle_database::execute() Multiple sql statements found or bound parameters not used properly in query!');
}
$this->do_query($sql, $params, SQL_QUERY_UPDATE);
return true;
}
/**
* 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 as for @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 $limitfrom is set).
* @return moodle_recordset instance
* @throws dml_exception if error
*/
public function get_recordset_sql($sql, array $params = null, $limitfrom = 0, $limitnum = 0) {
$limitfrom = (int)$limitfrom;
$limitnum = (int)$limitnum;
$limitfrom = max(0, $limitfrom);
$limitnum = max(0, $limitnum);
if ($limitfrom or $limitnum) {
$sql = $this->limit_to_top_n($sql, $limitfrom, $limitnum);
}
$result = $this->do_query($sql, $params, SQL_QUERY_SELECT, false);
return $this->create_recordset($result);
}
/**
* Perform a emulation for LIMIT(offset, limit)
*
* @param string $sql
* @param int $offset
* @param int $limit
* @return string sql
*/
private function limit_to_top_n($sql, $offset, $limit) {
// If there is no limit we can return immediatly
if ($limit < 1 && $offset < 1) {
return $sql;
}
// Make sure they are at least 0
$limit = max(0, (int)$limit);
$offset = max(0, (int)$offset);
// If limit is 0 set it to BITINT - 1
if (empty($limit)) {
$limit = 9223372036854775806;
} else {
$limit = $offset + $limit;
}
// Set up defaults for the next bit.
$columns = '*'; // Default to all columns
$columnnames = '*'; // As above
$firstcolumn = 'id'; // The default first column is id
$orderby = ''; // The order by of the main query
// We need to find all the columns so that we can request JUST the desired
// columns in the end transaction. We also need to do a couple of maintenance
// tasks on the columns seeing as they are going to be wrapped in a
// sub select.
//
// 1. Collect the first column to use for an order by if there isn't an
// explicit order by within the query.
// 2. Make we use the aliases for columns that have it because of next point.
// 3. Strip off table aliases they will be incorrect outside of the immediate
// sub select.
// 4. Give all constant columns a proper alias, this is required because
// of the subselect.
if (preg_match('#^(\s*SELECT\s+)(DISTINCT\s+)?(.*?)(\sFROM\s)#is', $sql, $columnmatches)) {
// Make sure we have some columns
if (!empty($columnmatches[3])) {
$columns = explode(',', $columnmatches[3]);
$columnnames = array();
$firstcolumn = null;
$constantcount = 0;
foreach ($columns as $key=>$column) {
// Trim, trim, trim, except during Movember.
$column = trim($column);
if (preg_match('#\sAS\s+(\w+)\s*$#si', $column, $matches)) {
// Make sure we use the column alias if available.
$column = $matches[1];
} else if (preg_match("#^'[^']*'$#", $column)) {
// Give constants an alias in the main query and use the
// alias for the new outer queries.
$constantcount++;
$column = 'constant_'.$constantcount;
$columns[$key] .= ' AS '.$column;
}
// Store the first column for later abuse.
if ($firstcolumn === null) {
$firstcolumn = $column;
}
// Remove any table aliases from the column name for the outer
// queries.
if (preg_match('#^\w+\.(.*)$#s', $column, $matches)) {
$column = $matches[1];
}
$columnnames[] = $column;
}
// Glue things back together
$columnnames = join(', ', $columnnames);
$columns = join(', ', $columns);
// Switch out the fixed main columns (added constant aliases).
$sql = str_replace($columnmatches[0], $columnmatches[1].$columnmatches[2].$columns.$columnmatches[4], $sql);
}
}
// Collect the orderby from the main query to use in the row number order by.
if (preg_match('#\sORDER\s+BY\s+([^)]+?)(GROUP\s+BY|$)#i', $sql, $matches)) {
// We need to remove it from the main query as well.
$sql = str_replace($matches[0], ' '.$matches[2], $sql);
$orderby = $matches[1];
} else {
// Default orderby to the first column.
$orderby = $firstcolumn;
}
// Remove any table aliases from the order by.
$orderby = preg_replace('#[^\s,]*\.([^\s,]*)#', '$1', $orderby);
// If the orderby is all tables everything will break, default to id.
if ($orderby == '*') {
$orderby = 'id';
}
// Build the inner outer query.
$sql = "SELECT TOP 9223372036854775806 ROW_NUMBER() OVER(ORDER BY $orderby) AS sqlsrvrownumber, $columnnames FROM ($sql) AS q";
// Build the outer most query.
$sql = "SELECT $columnnames FROM ($sql) AS q WHERE q.sqlsrvrownumber > $offset AND q.sqlsrvrownumber <= $limit";
// Return the now mangled query for use.
return $sql;
}
/**
* Create a record set and initialize with first row
*
* @param mixed $result
* @return sqlsrv_native_moodle_recordset
*/
protected function create_recordset($result) {
return new sqlsrv_native_moodle_recordset($result);
}
/**
* Get a number of records as an array of objects using a SQL statement.
*
* Return value as for @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 $limitfrom is set).
* @return array of objects, or empty array if no records were found
* @throws dml_exception if error
*/
public function get_records_sql($sql, array $params = null, $limitfrom = 0, $limitnum = 0) {
$rs = $this->get_recordset_sql($sql, $params, $limitfrom, $limitnum);
$results = array();
foreach ($rs as $row) {
$id = reset($row);
if (isset($results[$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);
}
$results[$id] = (object)$row;
}
$rs->close();
return $results;
}
/**
* Selects records and return values (first field) as an array using a SQL statement.
*
* @param string $sql The SQL query
* @param array $params array of sql parameters
* @return array of values
* @throws dml_exception if error
*/
public function get_fieldset_sql($sql, array $params = null) {
$rs = $this->get_recordset_sql($sql, $params);
$results = array ();
foreach ($rs as $row) {
$results[] = reset($row);
}
$rs->close();
return $results;
}
/**
* 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 $returnid
* @return bool|int true or new id
* @throws dml_exception if error
*/
public function insert_record_raw($table, $params, $returnid=true, $bulk=false, $customsequence=false) {
if (!is_array($params)) {
$params = (array)$params;
}
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;
// Disable IDENTITY column before inserting record with id
$sql = 'SET IDENTITY_INSERT {'.$table.'} ON'; // Yes, it' ON!!
$this->do_query($sql, null, SQL_QUERY_AUX);
} else {
unset($params['id']);
}
if (empty($params)) {
throw new coding_exception('moodle_database::insert_record_raw() no fields found.');
}
$fields = implode(',', array_keys($params));
$qms = array_fill(0, count($params), '?');
$qms = implode(',', $qms);
$sql = "INSERT INTO {" . $table . "} ($fields) VALUES($qms)";
$query_id = $this->do_query($sql, $params, SQL_QUERY_INSERT);
if ($customsequence) {
// Enable IDENTITY column after inserting record with id
$sql = 'SET IDENTITY_INSERT {'.$table.'} OFF'; // Yes, it' OFF!!
$this->do_query($sql, null, SQL_QUERY_AUX);
}
if ($returnid) {
$id = $this->sqlsrv_fetch_id();
return $id;
} else {
return true;
}
}
/**
* Get the ID of the current action
*
* @return mixed ID
*/
private function sqlsrv_fetch_id() {
$query_id = sqlsrv_query($this->sqlsrv, 'SELECT SCOPE_IDENTITY()');
if ($query_id === false) {
$dberr = $this->get_last_error();
return false;
}
$row = $this->sqlsrv_fetchrow($query_id);
return (int)$row[0];
}
/**
* Fetch a single row into an numbered array
*
* @param mixed $query_id
*/
private function sqlsrv_fetchrow($query_id) {
$row = sqlsrv_fetch_array($query_id, SQLSRV_FETCH_NUMERIC);
if ($row === false) {
$dberr = $this->get_last_error();
return false;
}
foreach ($row as $key => $value) {
$row[$key] = ($value === ' ' || $value === NULL) ? '' : $value;
}
return $row;
}
/**
* 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 $returnid Should the id of the newly created record entry be returned? If this option is not requested then true/false is returned.
* @return bool|int true or new id
* @throws dml_exception if error
*/
public function insert_record($table, $dataobject, $returnid = true, $bulk = false) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
$cleaned = array ();
foreach ($dataobject as $field => $value) {
if ($field === 'id') {
continue;
}
if (!isset($columns[$field])) {
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 $dataobject A data object with values for one or more fields in the record
* @return bool true
* @throws dml_exception if error
*/
public function import_record($table, $dataobject) {
if (!is_object($dataobject)) {
$dataobject = (object)$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);
}
$this->insert_record_raw($table, $cleaned, false, false, true);
return true;
}
/**
* Update record in database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception if error
*/
public function update_record_raw($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.');
}
$id = $params['id'];
unset($params['id']);
if (empty($params)) {
throw new coding_exception('moodle_database::update_record_raw() no fields found.');
}
$sets = array ();
foreach ($params as $field => $value) {
$sets[] = "$field = ?";
}
$params[] = $id; // last ? in WHERE condition
$sets = implode(',', $sets);
$sql = "UPDATE {".$table."} SET $sets WHERE id = ?";
$this->do_query($sql, $params, SQL_QUERY_UPDATE);
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 $dataobject An object with contents equal to fieldname=>fieldvalue. Must have an entry for 'id' to map to the table specified.
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception if error
*/
public function update_record($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);
}
return $this->update_record_raw($table, $cleaned, $bulk);
}
/**
* 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 $params array of sql parameters
* @return bool true
* @throws dml_exception if error
*/
public function set_field_select($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, $newvalue);
if (is_null($newvalue)) {
$newfield = "$newfield = NULL";
} else {
$newfield = "$newfield = ?";
array_unshift($params, $newvalue);
}
$sql = "UPDATE {".$table."} SET $newfield $select";
$this->do_query($sql, $params, SQL_QUERY_UPDATE);
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 $params array of sql parameters
* @return bool true
* @throws dml_exception if error
*/
public function delete_records_select($table, $select, array $params = null) {
if ($select) {
$select = "WHERE $select";
}
$sql = "DELETE FROM {".$table."} $select";
// we use SQL_QUERY_UPDATE because we do not know what is in general SQL, delete constant would not be accurate
$this->do_query($sql, $params, SQL_QUERY_UPDATE);
return true;
}
/// SQL helper functions
public function sql_cast_char2int($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 REAL) ';
} else {
return ' CAST(' . $this->sql_compare_text($fieldname) . ' AS REAL) ';
}
}
public function sql_ceil($fieldname) {
return ' CEILING('.$fieldname.')';
}
protected function get_collation() {
if (isset($this->collation)) {
return $this->collation;
}
if (!empty($this->dboptions['dbcollation'])) {
// perf speedup
$this->collation = $this->dboptions['dbcollation'];
return $this->collation;
}
// make some default
$this->collation = 'Latin1_General_CI_AI';
$sql = "SELECT CAST(DATABASEPROPERTYEX('$this->dbname', 'Collation') AS varchar(255)) AS SQLCollation";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
if ($result) {
if ($rawcolumn = sqlsrv_fetch_array($result, SQLSRV_FETCH_ASSOC)) {
$this->collation = reset($rawcolumn);
}
$this->free_result($result);
}
return $this->collation;
}
/**
* 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_ilike() expects bound parameters (? or :named)');
}
$collation = $this->get_collation();
$LIKE = $notlike ? 'NOT LIKE' : 'LIKE';
if ($casesensitive) {
$collation = str_replace('_CI', '_CS', $collation);
} else {
$collation = str_replace('_CS', '_CI', $collation);
}
if ($accentsensitive) {
$collation = str_replace('_AI', '_AS', $collation);
} else {
$collation = str_replace('_AS', '_AI', $collation);
}
return "$fieldname COLLATE $collation $LIKE $param ESCAPE '$escapechar'";
}
public function sql_concat() {
$arr = func_get_args();
foreach ($arr as $key => $ele) {
$arr[$key] = ' CAST('.$ele.' AS VARCHAR(255)) ';
}
$s = implode(' + ', $arr);
if ($s === '') {
return " '' ";
}
return " $s ";
}
public function sql_concat_join($separator = "' '", $elements = array ()) {
for ($n = count($elements) - 1; $n > 0; $n--) {
array_splice($elements, $n, 0, $separator);
}
$s = implode(' + ', $elements);
if ($s === '') {
return " '' ";
}
return " $s ";
}
public function sql_isempty($tablename, $fieldname, $nullablefield, $textfield) {
if ($textfield) {
return ' ('.$this->sql_compare_text($fieldname)." = '') ";
} else {
return " ($fieldname = '') ";
}
}
/**
* Returns the SQL text to be used to calculate the length in characters of one expression.
* @param string fieldname or expression to calculate its length in characters.
* @return string the piece of SQL code to be used in the statement.
*/
public function sql_length($fieldname) {
return ' LEN('.$fieldname.')';
}
public function sql_order_by_text($fieldname, $numchars = 32) {
return ' CONVERT(varchar, '.$fieldname.', '.$numchars.')';
}
/**
* Returns the SQL for returning searching one string for the location of another.
*/
public function sql_position($needle, $haystack) {
return "CHARINDEX(($needle), ($haystack))";
}
/**
* Returns the proper substr() SQL text used to extract substrings from DB
* NOTE: this was originally returning only function name
*
* @param string $expr some string field, no aggregates
* @param mixed $start integer or expression evaluating to int
* @param mixed $length optional integer or expression evaluating to int
* @return string sql fragment
*/
public function sql_substr($expr, $start, $length = false) {
if (count(func_get_args()) < 2) {
throw new coding_exception('moodle_database::sql_substr() requires at least two parameters',
'Originally this function was only returning name of SQL substring function, it now requires all parameters.');
}
if ($length === false) {
return "SUBSTRING($expr, $start, (LEN($expr) - $start + 1))";
} else {
return "SUBSTRING($expr, $start, $length)";
}
}
/// session locking
public function session_lock_supported() {
return true;
}
public function get_session_lock($rowid) {
if (!$this->session_lock_supported()) {
return;
}
parent::get_session_lock($rowid);
$fullname = $this->dbname.'-'.$this->prefix.'-session-'.$rowid;
$sql = "sp_getapplock '$fullname', 'Exclusive', 'Session', 120000";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
}
public function release_session_lock($rowid) {
if (!$this->session_lock_supported()) {
return;
}
parent::release_session_lock($rowid);
$fullname = $this->dbname.'-'.$this->prefix.'-session-'.$rowid;
$sql = "sp_releaseapplock '$fullname', 'Session'";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = sqlsrv_query($this->sqlsrv, $sql);
$this->query_end($result);
$this->free_result($result);
}
/// transactions
// NOTE:
// TODO -- should these be wrapped in query start/end? They arn't a query
// but information and error capture is nice. msk
/**
* Driver specific start of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function begin_transaction() {
$this->query_start('native sqlsrv_begin_transaction', NULL, SQL_QUERY_AUX);
$result = sqlsrv_begin_transaction($this->sqlsrv);
$this->query_end($result);
}
/**
* Driver specific commit of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function commit_transaction() {
$this->query_start('native sqlsrv_commit', NULL, SQL_QUERY_AUX);
$result = sqlsrv_commit($this->sqlsrv);
$this->query_end($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('native sqlsrv_rollback', NULL, SQL_QUERY_AUX);
$result = sqlsrv_rollback($this->sqlsrv);
$this->query_end($result);
}
}
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