src/Database/DBA.php

   1 <?php
   2
   3 namespace Friendica\Database;
   4
   5 // Do not use Core\Config in this class at risk of infinite loop.
   6 // Please use App->getConfigVariable() instead.
   7 //use Friendica\Core\Config;
   8
   9 use Friendica\Core\System;
  10 use Friendica\Util\DateTimeFormat;
  11 use PDO;
  12 use PDOException;
  13 use PDOStatement;
  14 use mysqli;
  15
  16 /**
  17  * @class MySQL database class
  18  *
  19  * This class is for the low level database stuff that does driver specific things.
  20  */
  21 class DBA
  22 {
  23         public static $connected = false;
  24
  25         private static $server_info = '';
  26         private static $db;
  27         private static $driver;
  28         private static $error = false;
  29         private static $errorno = 0;
  30         private static $affected_rows = 0;
  31         private static $in_transaction = false;
  32         private static $in_retrial = false;
  33         private static $relation = [];
  34         private static $db_serveraddr = '';
  35         private static $db_user = '';
  36         private static $db_pass = '';
  37         private static $db_name = '';
  38         private static $db_charset = '';
  39
  40         public static function connect($serveraddr, $user, $pass, $db, $charset = null)
  41         {
  42                 if (!is_null(self::$db) && self::connected()) {
  43                         return true;
  44                 }
  45
  46                 // We are storing these values for being able to perform a reconnect
  47                 self::$db_serveraddr = $serveraddr;
  48                 self::$db_user = $user;
  49                 self::$db_pass = $pass;
  50                 self::$db_name = $db;
  51                 self::$db_charset = $charset;
  52
  53                 $serveraddr = trim($serveraddr);
  54
  55                 $serverdata = explode(':', $serveraddr);
  56                 $server = $serverdata[0];
  57
  58                 if (count($serverdata) > 1) {
  59                         $port = trim($serverdata[1]);
  60                 }
  61
  62                 $server = trim($server);
  63                 $user = trim($user);
  64                 $pass = trim($pass);
  65                 $db = trim($db);
  66                 $charset = trim($charset);
  67
  68                 if (!(strlen($server) && strlen($user))) {
  69                         return false;
  70                 }
  71
  72                 if (class_exists('\PDO') && in_array('mysql', PDO::getAvailableDrivers())) {
  73                         self::$driver = 'pdo';
  74                         $connect = "mysql:host=".$server.";dbname=".$db;
  75
  76                         if (isset($port)) {
  77                                 $connect .= ";port=".$port;
  78                         }
  79
  80                         if ($charset) {
  81                                 $connect .= ";charset=".$charset;
  82                         }
  83
  84                         try {
  85                                 self::$db = @new PDO($connect, $user, $pass);
  86                                 self::$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
  87                                 self::$connected = true;
  88                         } catch (PDOException $e) {
  89                         }
  90                 }
  91
  92                 if (!self::$connected && class_exists('mysqli')) {
  93                         self::$driver = 'mysqli';
  94                         self::$db = @new mysqli($server, $user, $pass, $db, $port);
  95                         if (!mysqli_connect_errno()) {
  96                                 self::$connected = true;
  97
  98                                 if ($charset) {
  99                                         self::$db->set_charset($charset);
 100                                 }
 101                         }
 102                 }
 103
 104                 // No suitable SQL driver was found.
 105                 if (!self::$connected) {
 106                         self::$driver = null;
 107                         self::$db = null;
 108                 }
 109
 110                 return self::$connected;
 111         }
 112
 113         /**
 114          * Disconnects the current database connection
 115          */
 116         public static function disconnect()
 117         {
 118                 if (is_null(self::$db)) {
 119                         return;
 120                 }
 121
 122                 switch (self::$driver) {
 123                         case 'pdo':
 124                                 self::$db = null;
 125                                 break;
 126                         case 'mysqli':
 127                                 self::$db->close();
 128                                 self::$db = null;
 129                                 break;
 130                 }
 131         }
 132
 133         /**
 134          * Perform a reconnect of an existing database connection
 135          */
 136         public static function reconnect() {
 137                 self::disconnect();
 138
 139                 $ret = self::connect(self::$db_serveraddr, self::$db_user, self::$db_pass, self::$db_name, self::$db_charset);
 140                 return $ret;
 141         }
 142
 143         /**
 144          * Return the database object.
 145          * @return PDO|mysqli
 146          */
 147         public static function get_db()
 148         {
 149                 return self::$db;
 150         }
 151
 152         /**
 153          * @brief Returns the MySQL server version string
 154          *
 155          * This function discriminate between the deprecated mysql API and the current
 156          * object-oriented mysqli API. Example of returned string: 5.5.46-0+deb8u1
 157          *
 158          * @return string
 159          */
 160         public static function server_info() {
 161                 if (self::$server_info == '') {
 162                         switch (self::$driver) {
 163                                 case 'pdo':
 164                                         self::$server_info = self::$db->getAttribute(PDO::ATTR_SERVER_VERSION);
 165                                         break;
 166                                 case 'mysqli':
 167                                         self::$server_info = self::$db->server_info;
 168                                         break;
 169                         }
 170                 }
 171                 return self::$server_info;
 172         }
 173
 174         /**
 175          * @brief Returns the selected database name
 176          *
 177          * @return string
 178          */
 179         public static function database_name() {
 180                 $ret = self::p("SELECT DATABASE() AS `db`");
 181                 $data = self::inArray($ret);
 182                 return $data[0]['db'];
 183         }
 184
 185         /**
 186          * @brief Analyze a database query and log this if some conditions are met.
 187          *
 188          * @param string $query The database query that will be analyzed
 189          */
 190         private static function logIndex($query) {
 191                 $a = get_app();
 192
 193                 if (!$a->getConfigVariable('system', 'db_log_index')) {
 194                         return;
 195                 }
 196
 197                 // Don't explain an explain statement
 198                 if (strtolower(substr($query, 0, 7)) == "explain") {
 199                         return;
 200                 }
 201
 202                 // Only do the explain on "select", "update" and "delete"
 203                 if (!in_array(strtolower(substr($query, 0, 6)), ["select", "update", "delete"])) {
 204                         return;
 205                 }
 206
 207                 $r = self::p("EXPLAIN ".$query);
 208                 if (!DBM::is_result($r)) {
 209                         return;
 210                 }
 211
 212                 $watchlist = explode(',', $a->getConfigVariable('system', 'db_log_index_watch'));
 213                 $blacklist = explode(',', $a->getConfigVariable('system', 'db_log_index_blacklist'));
 214
 215                 while ($row = self::fetch($r)) {
 216                         if ((intval($a->getConfigVariable('system', 'db_loglimit_index')) > 0)) {
 217                                 $log = (in_array($row['key'], $watchlist) &&
 218                                         ($row['rows'] >= intval($a->getConfigVariable('system', 'db_loglimit_index'))));
 219                         } else {
 220                                 $log = false;
 221                         }
 222
 223                         if ((intval($a->getConfigVariable('system', 'db_loglimit_index_high')) > 0) && ($row['rows'] >= intval($a->getConfigVariable('system', 'db_loglimit_index_high')))) {
 224                                 $log = true;
 225                         }
 226
 227                         if (in_array($row['key'], $blacklist) || ($row['key'] == "")) {
 228                                 $log = false;
 229                         }
 230
 231                         if ($log) {
 232                                 $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
 233                                 @file_put_contents($a->getConfigVariable('system', 'db_log_index'), DateTimeFormat::utcNow()."\t".
 234                                                 $row['key']."\t".$row['rows']."\t".$row['Extra']."\t".
 235                                                 basename($backtrace[1]["file"])."\t".
 236                                                 $backtrace[1]["line"]."\t".$backtrace[2]["function"]."\t".
 237                                                 substr($query, 0, 2000)."\n", FILE_APPEND);
 238                         }
 239                 }
 240         }
 241
 242         public static function escape($str) {
 243                 switch (self::$driver) {
 244                         case 'pdo':
 245                                 return substr(@self::$db->quote($str, PDO::PARAM_STR), 1, -1);
 246                         case 'mysqli':
 247                                 return @self::$db->real_escape_string($str);
 248                 }
 249         }
 250
 251         public static function connected() {
 252                 $connected = false;
 253
 254                 if (is_null(self::$db)) {
 255                         return false;
 256                 }
 257
 258                 switch (self::$driver) {
 259                         case 'pdo':
 260                                 $r = self::p("SELECT 1");
 261                                 if (DBM::is_result($r)) {
 262                                         $row = self::inArray($r);
 263                                         $connected = ($row[0]['1'] == '1');
 264                                 }
 265                                 break;
 266                         case 'mysqli':
 267                                 $connected = self::$db->ping();
 268                                 break;
 269                 }
 270                 return $connected;
 271         }
 272
 273         /**
 274          * @brief Replaces ANY_VALUE() function by MIN() function,
 275          *  if the database server does not support ANY_VALUE().
 276          *
 277          * Considerations for Standard SQL, or MySQL with ONLY_FULL_GROUP_BY (default since 5.7.5).
 278          * ANY_VALUE() is available from MySQL 5.7.5 https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html
 279          * A standard fall-back is to use MIN().
 280          *
 281          * @param string $sql An SQL string without the values
 282          * @return string The input SQL string modified if necessary.
 283          */
 284         public static function any_value_fallback($sql) {
 285                 $server_info = self::server_info();
 286                 if (version_compare($server_info, '5.7.5', '<') ||
 287                         (stripos($server_info, 'MariaDB') !== false)) {
 288                         $sql = str_ireplace('ANY_VALUE(', 'MIN(', $sql);
 289                 }
 290                 return $sql;
 291         }
 292
 293         /**
 294          * @brief beautifies the query - useful for "SHOW PROCESSLIST"
 295          *
 296          * This is safe when we bind the parameters later.
 297          * The parameter values aren't part of the SQL.
 298          *
 299          * @param string $sql An SQL string without the values
 300          * @return string The input SQL string modified if necessary.
 301          */
 302         public static function clean_query($sql) {
 303                 $search = ["\t", "\n", "\r", "  "];
 304                 $replace = [' ', ' ', ' ', ' '];
 305                 do {
 306                         $oldsql = $sql;
 307                         $sql = str_replace($search, $replace, $sql);
 308                 } while ($oldsql != $sql);
 309
 310                 return $sql;
 311         }
 312
 313
 314         /**
 315          * @brief Replaces the ? placeholders with the parameters in the $args array
 316          *
 317          * @param string $sql SQL query
 318          * @param array $args The parameters that are to replace the ? placeholders
 319          * @return string The replaced SQL query
 320          */
 321         private static function replaceParameters($sql, $args) {
 322                 $offset = 0;
 323                 foreach ($args AS $param => $value) {
 324                         if (is_int($args[$param]) || is_float($args[$param])) {
 325                                 $replace = intval($args[$param]);
 326                         } else {
 327                                 $replace = "'".self::escape($args[$param])."'";
 328                         }
 329
 330                         $pos = strpos($sql, '?', $offset);
 331                         if ($pos !== false) {
 332                                 $sql = substr_replace($sql, $replace, $pos, 1);
 333                         }
 334                         $offset = $pos + strlen($replace);
 335                 }
 336                 return $sql;
 337         }
 338
 339         /**
 340          * @brief Convert parameter array to an universal form
 341          * @param array $args Parameter array
 342          * @return array universalized parameter array
 343          */
 344         private static function getParam($args) {
 345                 unset($args[0]);
 346
 347                 // When the second function parameter is an array then use this as the parameter array
 348                 if ((count($args) > 0) && (is_array($args[1]))) {
 349                         return $args[1];
 350                 } else {
 351                         return $args;
 352                 }
 353         }
 354
 355         /**
 356          * @brief Executes a prepared statement that returns data
 357          * @usage Example: $r = p("SELECT * FROM `item` WHERE `guid` = ?", $guid);
 358          *
 359          * Please only use it with complicated queries.
 360          * For all regular queries please use dba::select or dba::exists
 361          *
 362          * @param string $sql SQL statement
 363          * @return bool|object statement object or result object
 364          */
 365         public static function p($sql) {
 366                 $a = get_app();
 367
 368                 $stamp1 = microtime(true);
 369
 370                 $params = self::getParam(func_get_args());
 371
 372                 // Renumber the array keys to be sure that they fit
 373                 $i = 0;
 374                 $args = [];
 375                 foreach ($params AS $param) {
 376                         // Avoid problems with some MySQL servers and boolean values. See issue #3645
 377                         if (is_bool($param)) {
 378                                 $param = (int)$param;
 379                         }
 380                         $args[++$i] = $param;
 381                 }
 382
 383                 if (!self::$connected) {
 384                         return false;
 385                 }
 386
 387                 if ((substr_count($sql, '?') != count($args)) && (count($args) > 0)) {
 388                         // Question: Should we continue or stop the query here?
 389                         logger('Parameter mismatch. Query "'.$sql.'" - Parameters '.print_r($args, true), LOGGER_DEBUG);
 390                 }
 391
 392                 $sql = self::clean_query($sql);
 393                 $sql = self::any_value_fallback($sql);
 394
 395                 $orig_sql = $sql;
 396
 397                 if ($a->getConfigValue('system', 'db_callstack')) {
 398                         $sql = "/*".System::callstack()." */ ".$sql;
 399                 }
 400
 401                 self::$error = '';
 402                 self::$errorno = 0;
 403                 self::$affected_rows = 0;
 404
 405                 // We have to make some things different if this function is called from "e"
 406                 $trace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2);
 407
 408                 if (isset($trace[1])) {
 409                         $called_from = $trace[1];
 410                 } else {
 411                         // We use just something that is defined to avoid warnings
 412                         $called_from = $trace[0];
 413                 }
 414                 // We are having an own error logging in the function "e"
 415                 $called_from_e = ($called_from['function'] == 'e');
 416
 417                 switch (self::$driver) {
 418                         case 'pdo':
 419                                 // If there are no arguments we use "query"
 420                                 if (count($args) == 0) {
 421                                         if (!$retval = self::$db->query($sql)) {
 422                                                 $errorInfo = self::$db->errorInfo();
 423                                                 self::$error = $errorInfo[2];
 424                                                 self::$errorno = $errorInfo[1];
 425                                                 $retval = false;
 426                                                 break;
 427                                         }
 428                                         self::$affected_rows = $retval->rowCount();
 429                                         break;
 430                                 }
 431
 432                                 if (!$stmt = self::$db->prepare($sql)) {
 433                                         $errorInfo = self::$db->errorInfo();
 434                                         self::$error = $errorInfo[2];
 435                                         self::$errorno = $errorInfo[1];
 436                                         $retval = false;
 437                                         break;
 438                                 }
 439
 440                                 foreach ($args AS $param => $value) {
 441                                         if (is_int($args[$param])) {
 442                                                 $data_type = PDO::PARAM_INT;
 443                                         } else {
 444                                                 $data_type = PDO::PARAM_STR;
 445                                         }
 446                                         $stmt->bindParam($param, $args[$param], $data_type);
 447                                 }
 448
 449                                 if (!$stmt->execute()) {
 450                                         $errorInfo = $stmt->errorInfo();
 451                                         self::$error = $errorInfo[2];
 452                                         self::$errorno = $errorInfo[1];
 453                                         $retval = false;
 454                                 } else {
 455                                         $retval = $stmt;
 456                                         self::$affected_rows = $retval->rowCount();
 457                                 }
 458                                 break;
 459                         case 'mysqli':
 460                                 // There are SQL statements that cannot be executed with a prepared statement
 461                                 $parts = explode(' ', $orig_sql);
 462                                 $command = strtolower($parts[0]);
 463                                 $can_be_prepared = in_array($command, ['select', 'update', 'insert', 'delete']);
 464
 465                                 // The fallback routine is called as well when there are no arguments
 466                                 if (!$can_be_prepared || (count($args) == 0)) {
 467                                         $retval = self::$db->query(self::replaceParameters($sql, $args));
 468                                         if (self::$db->errno) {
 469                                                 self::$error = self::$db->error;
 470                                                 self::$errorno = self::$db->errno;
 471                                                 $retval = false;
 472                                         } else {
 473                                                 if (isset($retval->num_rows)) {
 474                                                         self::$affected_rows = $retval->num_rows;
 475                                                 } else {
 476                                                         self::$affected_rows = self::$db->affected_rows;
 477                                                 }
 478                                         }
 479                                         break;
 480                                 }
 481
 482                                 $stmt = self::$db->stmt_init();
 483
 484                                 if (!$stmt->prepare($sql)) {
 485                                         self::$error = $stmt->error;
 486                                         self::$errorno = $stmt->errno;
 487                                         $retval = false;
 488                                         break;
 489                                 }
 490
 491                                 $param_types = '';
 492                                 $values = [];
 493                                 foreach ($args AS $param => $value) {
 494                                         if (is_int($args[$param])) {
 495                                                 $param_types .= 'i';
 496                                         } elseif (is_float($args[$param])) {
 497                                                 $param_types .= 'd';
 498                                         } elseif (is_string($args[$param])) {
 499                                                 $param_types .= 's';
 500                                         } else {
 501                                                 $param_types .= 'b';
 502                                         }
 503                                         $values[] = &$args[$param];
 504                                 }
 505
 506                                 if (count($values) > 0) {
 507                                         array_unshift($values, $param_types);
 508                                         call_user_func_array([$stmt, 'bind_param'], $values);
 509                                 }
 510
 511                                 if (!$stmt->execute()) {
 512                                         self::$error = self::$db->error;
 513                                         self::$errorno = self::$db->errno;
 514                                         $retval = false;
 515                                 } else {
 516                                         $stmt->store_result();
 517                                         $retval = $stmt;
 518                                         self::$affected_rows = $retval->affected_rows;
 519                                 }
 520                                 break;
 521                 }
 522
 523                 // We are having an own error logging in the function "e"
 524                 if ((self::$errorno != 0) && !$called_from_e) {
 525                         // We have to preserve the error code, somewhere in the logging it get lost
 526                         $error = self::$error;
 527                         $errorno = self::$errorno;
 528
 529                         logger('DB Error '.self::$errorno.': '.self::$error."\n".
 530                                 System::callstack(8)."\n".self::replaceParameters($sql, $args));
 531
 532                         // On a lost connection we try to reconnect - but only once.
 533                         if ($errorno == 2006) {
 534                                 if (self::$in_retrial || !self::reconnect()) {
 535                                         // It doesn't make sense to continue when the database connection was lost
 536                                         if (self::$in_retrial) {
 537                                                 logger('Giving up retrial because of database error '.$errorno.': '.$error);
 538                                         } else {
 539                                                 logger("Couldn't reconnect after database error ".$errorno.': '.$error);
 540                                         }
 541                                         exit(1);
 542                                 } else {
 543                                         // We try it again
 544                                         logger('Reconnected after database error '.$errorno.': '.$error);
 545                                         self::$in_retrial = true;
 546                                         $ret = self::p($sql, $args);
 547                                         self::$in_retrial = false;
 548                                         return $ret;
 549                                 }
 550                         }
 551
 552                         self::$error = $error;
 553                         self::$errorno = $errorno;
 554                 }
 555
 556                 $a->save_timestamp($stamp1, 'database');
 557
 558                 if ($a->getConfigValue('system', 'db_log')) {
 559                         $stamp2 = microtime(true);
 560                         $duration = (float)($stamp2 - $stamp1);
 561
 562                         if (($duration > $a->getConfigValue('system', 'db_loglimit'))) {
 563                                 $duration = round($duration, 3);
 564                                 $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
 565
 566                                 @file_put_contents($a->getConfigValue('system', 'db_log'), DateTimeFormat::utcNow()."\t".$duration."\t".
 567                                                 basename($backtrace[1]["file"])."\t".
 568                                                 $backtrace[1]["line"]."\t".$backtrace[2]["function"]."\t".
 569                                                 substr(self::replaceParameters($sql, $args), 0, 2000)."\n", FILE_APPEND);
 570                         }
 571                 }
 572                 return $retval;
 573         }
 574
 575         /**
 576          * @brief Executes a prepared statement like UPDATE or INSERT that doesn't return data
 577          *
 578          * Please use dba::delete, dba::insert, dba::update, ... instead
 579          *
 580          * @param string $sql SQL statement
 581          * @return boolean Was the query successfull? False is returned only if an error occurred
 582          */
 583         public static function e($sql) {
 584                 $a = get_app();
 585
 586                 $stamp = microtime(true);
 587
 588                 $params = self::getParam(func_get_args());
 589
 590                 // In a case of a deadlock we are repeating the query 20 times
 591                 $timeout = 20;
 592
 593                 do {
 594                         $stmt = self::p($sql, $params);
 595
 596                         if (is_bool($stmt)) {
 597                                 $retval = $stmt;
 598                         } elseif (is_object($stmt)) {
 599                                 $retval = true;
 600                         } else {
 601                                 $retval = false;
 602                         }
 603
 604                         self::close($stmt);
 605
 606                 } while ((self::$errorno == 1213) && (--$timeout > 0));
 607
 608                 if (self::$errorno != 0) {
 609                         // We have to preserve the error code, somewhere in the logging it get lost
 610                         $error = self::$error;
 611                         $errorno = self::$errorno;
 612
 613                         logger('DB Error '.self::$errorno.': '.self::$error."\n".
 614                                 System::callstack(8)."\n".self::replaceParameters($sql, $params));
 615
 616                         // On a lost connection we simply quit.
 617                         // A reconnect like in self::p could be dangerous with modifications
 618                         if ($errorno == 2006) {
 619                                 logger('Giving up because of database error '.$errorno.': '.$error);
 620                                 exit(1);
 621                         }
 622
 623                         self::$error = $error;
 624                         self::$errorno = $errorno;
 625                 }
 626
 627                 $a->save_timestamp($stamp, "database_write");
 628
 629                 return $retval;
 630         }
 631
 632         /**
 633          * @brief Check if data exists
 634          *
 635          * @param string $table Table name
 636          * @param array $condition array of fields for condition
 637          *
 638          * @return boolean Are there rows for that condition?
 639          */
 640         public static function exists($table, $condition) {
 641                 if (empty($table)) {
 642                         return false;
 643                 }
 644
 645                 $fields = [];
 646
 647                 if (empty($condition)) {
 648                         return DBStructure::existsTable($table);
 649                 }
 650
 651                 reset($condition);
 652                 $first_key = key($condition);
 653                 if (!is_int($first_key)) {
 654                         $fields = [$first_key];
 655                 }
 656
 657                 $stmt = self::select($table, $fields, $condition, ['limit' => 1]);
 658
 659                 if (is_bool($stmt)) {
 660                         $retval = $stmt;
 661                 } else {
 662                         $retval = (self::num_rows($stmt) > 0);
 663                 }
 664
 665                 self::close($stmt);
 666
 667                 return $retval;
 668         }
 669
 670         /**
 671          * Fetches the first row
 672          *
 673          * Please use dba::selectFirst or dba::exists whenever this is possible.
 674          *
 675          * @brief Fetches the first row
 676          * @param string $sql SQL statement
 677          * @return array first row of query
 678          */
 679         public static function fetch_first($sql) {
 680                 $params = self::getParam(func_get_args());
 681
 682                 $stmt = self::p($sql, $params);
 683
 684                 if (is_bool($stmt)) {
 685                         $retval = $stmt;
 686                 } else {
 687                         $retval = self::fetch($stmt);
 688                 }
 689
 690                 self::close($stmt);
 691
 692                 return $retval;
 693         }
 694
 695         /**
 696          * @brief Returns the number of affected rows of the last statement
 697          *
 698          * @return int Number of rows
 699          */
 700         public static function affected_rows() {
 701                 return self::$affected_rows;
 702         }
 703
 704         /**
 705          * @brief Returns the number of columns of a statement
 706          *
 707          * @param object Statement object
 708          * @return int Number of columns
 709          */
 710         public static function columnCount($stmt) {
 711                 if (!is_object($stmt)) {
 712                         return 0;
 713                 }
 714                 switch (self::$driver) {
 715                         case 'pdo':
 716                                 return $stmt->columnCount();
 717                         case 'mysqli':
 718                                 return $stmt->field_count;
 719                 }
 720                 return 0;
 721         }
 722         /**
 723          * @brief Returns the number of rows of a statement
 724          *
 725          * @param PDOStatement|mysqli_result|mysqli_stmt Statement object
 726          * @return int Number of rows
 727          */
 728         public static function num_rows($stmt) {
 729                 if (!is_object($stmt)) {
 730                         return 0;
 731                 }
 732                 switch (self::$driver) {
 733                         case 'pdo':
 734                                 return $stmt->rowCount();
 735                         case 'mysqli':
 736                                 return $stmt->num_rows;
 737                 }
 738                 return 0;
 739         }
 740
 741         /**
 742          * @brief Fetch a single row
 743          *
 744          * @param mixed $stmt statement object
 745          * @return array current row
 746          */
 747         public static function fetch($stmt) {
 748                 $a = get_app();
 749
 750                 $stamp1 = microtime(true);
 751
 752                 $columns = [];
 753
 754                 if (!is_object($stmt)) {
 755                         return false;
 756                 }
 757
 758                 switch (self::$driver) {
 759                         case 'pdo':
 760                                 $columns = $stmt->fetch(PDO::FETCH_ASSOC);
 761                                 break;
 762                         case 'mysqli':
 763                                 if (get_class($stmt) == 'mysqli_result') {
 764                                         $columns = $stmt->fetch_assoc();
 765                                         break;
 766                                 }
 767
 768                                 // This code works, but is slow
 769
 770                                 // Bind the result to a result array
 771                                 $cols = [];
 772
 773                                 $cols_num = [];
 774                                 for ($x = 0; $x < $stmt->field_count; $x++) {
 775                                         $cols[] = &$cols_num[$x];
 776                                 }
 777
 778                                 call_user_func_array([$stmt, 'bind_result'], $cols);
 779
 780                                 if (!$stmt->fetch()) {
 781                                         return false;
 782                                 }
 783
 784                                 // The slow part:
 785                                 // We need to get the field names for the array keys
 786                                 // It seems that there is no better way to do this.
 787                                 $result = $stmt->result_metadata();
 788                                 $fields = $result->fetch_fields();
 789
 790                                 foreach ($cols_num AS $param => $col) {
 791                                         $columns[$fields[$param]->name] = $col;
 792                                 }
 793                 }
 794
 795                 $a->save_timestamp($stamp1, 'database');
 796
 797                 return $columns;
 798         }
 799
 800         /**
 801          * @brief Insert a row into a table
 802          *
 803          * @param string $table Table name
 804          * @param array $param parameter array
 805          * @param bool $on_duplicate_update Do an update on a duplicate entry
 806          *
 807          * @return boolean was the insert successfull?
 808          */
 809         public static function insert($table, $param, $on_duplicate_update = false) {
 810
 811                 if (empty($table) || empty($param)) {
 812                         logger('Table and fields have to be set');
 813                         return false;
 814                 }
 815
 816                 $sql = "INSERT INTO `".self::escape($table)."` (`".implode("`, `", array_keys($param))."`) VALUES (".
 817                         substr(str_repeat("?, ", count($param)), 0, -2).")";
 818
 819                 if ($on_duplicate_update) {
 820                         $sql .= " ON DUPLICATE KEY UPDATE `".implode("` = ?, `", array_keys($param))."` = ?";
 821
 822                         $values = array_values($param);
 823                         $param = array_merge_recursive($values, $values);
 824                 }
 825
 826                 return self::e($sql, $param);
 827         }
 828
 829         /**
 830          * @brief Fetch the id of the last insert command
 831          *
 832          * @return integer Last inserted id
 833          */
 834         public static function lastInsertId() {
 835                 switch (self::$driver) {
 836                         case 'pdo':
 837                                 $id = self::$db->lastInsertId();
 838                                 break;
 839                         case 'mysqli':
 840                                 $id = self::$db->insert_id;
 841                                 break;
 842                 }
 843                 return $id;
 844         }
 845
 846         /**
 847          * @brief Locks a table for exclusive write access
 848          *
 849          * This function can be extended in the future to accept a table array as well.
 850          *
 851          * @param string $table Table name
 852          *
 853          * @return boolean was the lock successful?
 854          */
 855         public static function lock($table) {
 856                 // See here: https://dev.mysql.com/doc/refman/5.7/en/lock-tables-and-transactions.html
 857                 if (self::$driver == 'pdo') {
 858                         self::e("SET autocommit=0");
 859                         self::$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);
 860                 } else {
 861                         self::$db->autocommit(false);
 862                 }
 863
 864                 $success = self::e("LOCK TABLES `".self::escape($table)."` WRITE");
 865
 866                 if (self::$driver == 'pdo') {
 867                         self::$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
 868                 }
 869
 870                 if (!$success) {
 871                         if (self::$driver == 'pdo') {
 872                                 self::e("SET autocommit=1");
 873                         } else {
 874                                 self::$db->autocommit(true);
 875                         }
 876                 } else {
 877                         self::$in_transaction = true;
 878                 }
 879                 return $success;
 880         }
 881
 882         /**
 883          * @brief Unlocks all locked tables
 884          *
 885          * @return boolean was the unlock successful?
 886          */
 887         public static function unlock() {
 888                 // See here: https://dev.mysql.com/doc/refman/5.7/en/lock-tables-and-transactions.html
 889                 self::performCommit();
 890
 891                 if (self::$driver == 'pdo') {
 892                         self::$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);
 893                 }
 894
 895                 $success = self::e("UNLOCK TABLES");
 896
 897                 if (self::$driver == 'pdo') {
 898                         self::$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
 899                         self::e("SET autocommit=1");
 900                 } else {
 901                         self::$db->autocommit(true);
 902                 }
 903
 904                 self::$in_transaction = false;
 905                 return $success;
 906         }
 907
 908         /**
 909          * @brief Starts a transaction
 910          *
 911          * @return boolean Was the command executed successfully?
 912          */
 913         public static function transaction() {
 914                 if (!self::performCommit()) {
 915                         return false;
 916                 }
 917
 918                 switch (self::$driver) {
 919                         case 'pdo':
 920                                 if (self::$db->inTransaction()) {
 921                                         break;
 922                                 }
 923                                 if (!self::$db->beginTransaction()) {
 924                                         return false;
 925                                 }
 926                                 break;
 927                         case 'mysqli':
 928                                 if (!self::$db->begin_transaction()) {
 929                                         return false;
 930                                 }
 931                                 break;
 932                 }
 933
 934                 self::$in_transaction = true;
 935                 return true;
 936         }
 937
 938         private static function performCommit()
 939         {
 940                 switch (self::$driver) {
 941                         case 'pdo':
 942                                 if (!self::$db->inTransaction()) {
 943                                         return true;
 944                                 }
 945                                 return self::$db->commit();
 946                         case 'mysqli':
 947                                 return self::$db->commit();
 948                 }
 949                 return true;
 950         }
 951
 952         /**
 953          * @brief Does a commit
 954          *
 955          * @return boolean Was the command executed successfully?
 956          */
 957         public static function commit() {
 958                 if (!self::performCommit()) {
 959                         return false;
 960                 }
 961                 self::$in_transaction = false;
 962                 return true;
 963         }
 964
 965         /**
 966          * @brief Does a rollback
 967          *
 968          * @return boolean Was the command executed successfully?
 969          */
 970         public static function rollback() {
 971                 $ret = false;
 972
 973                 switch (self::$driver) {
 974                         case 'pdo':
 975                                 if (!self::$db->inTransaction()) {
 976                                         $ret = true;
 977                                         break;
 978                                 }
 979                                 $ret = self::$db->rollBack();
 980                                 break;
 981                         case 'mysqli':
 982                                 $ret = self::$db->rollback();
 983                                 break;
 984                 }
 985                 self::$in_transaction = false;
 986                 return $ret;
 987         }
 988
 989         /**
 990          * @brief Build the array with the table relations
 991          *
 992          * The array is build from the database definitions in DBStructure.php
 993          *
 994          * This process must only be started once, since the value is cached.
 995          */
 996         private static function buildRelationData() {
 997                 $definition = DBStructure::definition();
 998
 999                 foreach ($definition AS $table => $structure) {
1000                         foreach ($structure['fields'] AS $field => $field_struct) {
1001                                 if (isset($field_struct['relation'])) {
1002                                         foreach ($field_struct['relation'] AS $rel_table => $rel_field) {
1003                                                 self::$relation[$rel_table][$rel_field][$table][] = $field;
1004                                         }
1005                                 }
1006                         }
1007                 }
1008         }
1009
1010         /**
1011          * @brief Delete a row from a table
1012          *
1013          * @param string  $table       Table name
1014          * @param array   $conditions  Field condition(s)
1015          * @param array   $options
1016          *                - cascade: If true we delete records in other tables that depend on the one we're deleting through
1017          *                           relations (default: true)
1018          * @param boolean $in_process  Internal use: Only do a commit after the last delete
1019          * @param array   $callstack   Internal use: prevent endless loops
1020          *
1021          * @return boolean|array was the delete successful? When $in_process is set: deletion data
1022          */
1023         public static function delete($table, array $conditions, array $options = [], $in_process = false, array &$callstack = [])
1024         {
1025                 if (empty($table) || empty($conditions)) {
1026                         logger('Table and conditions have to be set');
1027                         return false;
1028                 }
1029
1030                 $commands = [];
1031
1032                 // Create a key for the loop prevention
1033                 $key = $table . ':' . json_encode($conditions);
1034
1035                 // We quit when this key already exists in the callstack.
1036                 if (isset($callstack[$key])) {
1037                         return $commands;
1038                 }
1039
1040                 $callstack[$key] = true;
1041
1042                 $table = self::escape($table);
1043
1044                 $commands[$key] = ['table' => $table, 'conditions' => $conditions];
1045
1046                 $cascade = defaults($options, 'cascade', true);
1047
1048                 // To speed up the whole process we cache the table relations
1049                 if ($cascade && count(self::$relation) == 0) {
1050                         self::buildRelationData();
1051                 }
1052
1053                 // Is there a relation entry for the table?
1054                 if ($cascade && isset(self::$relation[$table])) {
1055                         // We only allow a simple "one field" relation.
1056                         $field = array_keys(self::$relation[$table])[0];
1057                         $rel_def = array_values(self::$relation[$table])[0];
1058
1059                         // Create a key for preventing double queries
1060                         $qkey = $field . '-' . $table . ':' . json_encode($conditions);
1061
1062                         // When the search field is the relation field, we don't need to fetch the rows
1063                         // This is useful when the leading record is already deleted in the frontend but the rest is done in the backend
1064                         if ((count($conditions) == 1) && ($field == array_keys($conditions)[0])) {
1065                                 foreach ($rel_def AS $rel_table => $rel_fields) {
1066                                         foreach ($rel_fields AS $rel_field) {
1067                                                 $retval = self::delete($rel_table, [$rel_field => array_values($conditions)[0]], $options, true, $callstack);
1068                                                 $commands = array_merge($commands, $retval);
1069                                         }
1070                                 }
1071                                 // We quit when this key already exists in the callstack.
1072                         } elseif (!isset($callstack[$qkey])) {
1073
1074                                 $callstack[$qkey] = true;
1075
1076                                 // Fetch all rows that are to be deleted
1077                                 $data = self::select($table, [$field], $conditions);
1078
1079                                 while ($row = self::fetch($data)) {
1080                                         // Now we accumulate the delete commands
1081                                         $retval = self::delete($table, [$field => $row[$field]], $options, true, $callstack);
1082                                         $commands = array_merge($commands, $retval);
1083                                 }
1084
1085                                 self::close($data);
1086
1087                                 // Since we had split the delete command we don't need the original command anymore
1088                                 unset($commands[$key]);
1089                         }
1090                 }
1091
1092                 if (!$in_process) {
1093                         // Now we finalize the process
1094                         $do_transaction = !self::$in_transaction;
1095
1096                         if ($do_transaction) {
1097                                 self::transaction();
1098                         }
1099
1100                         $compacted = [];
1101                         $counter = [];
1102
1103                         foreach ($commands AS $command) {
1104                                 $conditions = $command['conditions'];
1105                                 reset($conditions);
1106                                 $first_key = key($conditions);
1107
1108                                 $condition_string = self::buildCondition($conditions);
1109
1110                                 if ((count($command['conditions']) > 1) || is_int($first_key)) {
1111                                         $sql = "DELETE FROM `" . $command['table'] . "`" . $condition_string;
1112                                         logger(self::replaceParameters($sql, $conditions), LOGGER_DATA);
1113
1114                                         if (!self::e($sql, $conditions)) {
1115                                                 if ($do_transaction) {
1116                                                         self::rollback();
1117                                                 }
1118                                                 return false;
1119                                         }
1120                                 } else {
1121                                         $key_table = $command['table'];
1122                                         $key_condition = array_keys($command['conditions'])[0];
1123                                         $value = array_values($command['conditions'])[0];
1124
1125                                         // Split the SQL queries in chunks of 100 values
1126                                         // We do the $i stuff here to make the code better readable
1127                                         $i = isset($counter[$key_table][$key_condition]) ? $counter[$key_table][$key_condition] : 0;
1128                                         if (isset($compacted[$key_table][$key_condition][$i]) && count($compacted[$key_table][$key_condition][$i]) > 100) {
1129                                                 ++$i;
1130                                         }
1131
1132                                         $compacted[$key_table][$key_condition][$i][$value] = $value;
1133                                         $counter[$key_table][$key_condition] = $i;
1134                                 }
1135                         }
1136                         foreach ($compacted AS $table => $values) {
1137                                 foreach ($values AS $field => $field_value_list) {
1138                                         foreach ($field_value_list AS $field_values) {
1139                                                 $sql = "DELETE FROM `" . $table . "` WHERE `" . $field . "` IN (" .
1140                                                         substr(str_repeat("?, ", count($field_values)), 0, -2) . ");";
1141
1142                                                 logger(self::replaceParameters($sql, $field_values), LOGGER_DATA);
1143
1144                                                 if (!self::e($sql, $field_values)) {
1145                                                         if ($do_transaction) {
1146                                                                 self::rollback();
1147                                                         }
1148                                                         return false;
1149                                                 }
1150                                         }
1151                                 }
1152                         }
1153                         if ($do_transaction) {
1154                                 self::commit();
1155                         }
1156                         return true;
1157                 }
1158
1159                 return $commands;
1160         }
1161
1162         /**
1163          * @brief Updates rows
1164          *
1165          * Updates rows in the database. When $old_fields is set to an array,
1166          * the system will only do an update if the fields in that array changed.
1167          *
1168          * Attention:
1169          * Only the values in $old_fields are compared.
1170          * This is an intentional behaviour.
1171          *
1172          * Example:
1173          * We include the timestamp field in $fields but not in $old_fields.
1174          * Then the row will only get the new timestamp when the other fields had changed.
1175          *
1176          * When $old_fields is set to a boolean value the system will do this compare itself.
1177          * When $old_fields is set to "true" the system will do an insert if the row doesn't exists.
1178          *
1179          * Attention:
1180          * Only set $old_fields to a boolean value when you are sure that you will update a single row.
1181          * When you set $old_fields to "true" then $fields must contain all relevant fields!
1182          *
1183          * @param string $table Table name
1184          * @param array $fields contains the fields that are updated
1185          * @param array $condition condition array with the key values
1186          * @param array|boolean $old_fields array with the old field values that are about to be replaced (true = update on duplicate)
1187          *
1188          * @return boolean was the update successfull?
1189          */
1190         public static function update($table, $fields, $condition, $old_fields = []) {
1191
1192                 if (empty($table) || empty($fields) || empty($condition)) {
1193                         logger('Table, fields and condition have to be set');
1194                         return false;
1195                 }
1196
1197                 $table = self::escape($table);
1198
1199                 $condition_string = self::buildCondition($condition);
1200
1201                 if (is_bool($old_fields)) {
1202                         $do_insert = $old_fields;
1203
1204                         $old_fields = self::selectFirst($table, [], $condition);
1205
1206                         if (is_bool($old_fields)) {
1207                                 if ($do_insert) {
1208                                         $values = array_merge($condition, $fields);
1209                                         return self::insert($table, $values, $do_insert);
1210                                 }
1211                                 $old_fields = [];
1212                         }
1213                 }
1214
1215                 $do_update = (count($old_fields) == 0);
1216
1217                 foreach ($old_fields AS $fieldname => $content) {
1218                         if (isset($fields[$fieldname])) {
1219                                 if ($fields[$fieldname] == $content) {
1220                                         unset($fields[$fieldname]);
1221                                 } else {
1222                                         $do_update = true;
1223                                 }
1224                         }
1225                 }
1226
1227                 if (!$do_update || (count($fields) == 0)) {
1228                         return true;
1229                 }
1230
1231                 $sql = "UPDATE `".$table."` SET `".
1232                         implode("` = ?, `", array_keys($fields))."` = ?".$condition_string;
1233
1234                 $params1 = array_values($fields);
1235                 $params2 = array_values($condition);
1236                 $params = array_merge_recursive($params1, $params2);
1237
1238                 return self::e($sql, $params);
1239         }
1240
1241         /**
1242          * Retrieve a single record from a table and returns it in an associative array
1243          *
1244          * @brief Retrieve a single record from a table
1245          * @param string $table
1246          * @param array  $fields
1247          * @param array  $condition
1248          * @param array  $params
1249          * @return bool|array
1250          * @see self::select
1251          */
1252         public static function selectFirst($table, array $fields = [], array $condition = [], $params = [])
1253         {
1254                 $params['limit'] = 1;
1255                 $result = self::select($table, $fields, $condition, $params);
1256
1257                 if (is_bool($result)) {
1258                         return $result;
1259                 } else {
1260                         $row = self::fetch($result);
1261                         self::close($result);
1262                         return $row;
1263                 }
1264         }
1265
1266         /**
1267          * @brief Select rows from a table
1268          *
1269          * @param string $table     Table name
1270          * @param array  $fields    Array of selected fields, empty for all
1271          * @param array  $condition Array of fields for condition
1272          * @param array  $params    Array of several parameters
1273          *
1274          * @return boolean|object
1275          *
1276          * Example:
1277          * $table = "item";
1278          * $fields = array("id", "uri", "uid", "network");
1279          *
1280          * $condition = array("uid" => 1, "network" => 'dspr');
1281          * or:
1282          * $condition = array("`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr');
1283          *
1284          * $params = array("order" => array("id", "received" => true), "limit" => 10);
1285          *
1286          * $data = dba::select($table, $fields, $condition, $params);
1287          */
1288         public static function select($table, array $fields = [], array $condition = [], array $params = [])
1289         {
1290                 if ($table == '') {
1291                         return false;
1292                 }
1293
1294                 $table = self::escape($table);
1295
1296                 if (count($fields) > 0) {
1297                         $select_fields = "`" . implode("`, `", array_values($fields)) . "`";
1298                 } else {
1299                         $select_fields = "*";
1300                 }
1301
1302                 $condition_string = self::buildCondition($condition);
1303
1304                 $param_string = self::buildParameter($params);
1305
1306                 $sql = "SELECT " . $select_fields . " FROM `" . $table . "`" . $condition_string . $param_string;
1307
1308                 $result = self::p($sql, $condition);
1309
1310                 return $result;
1311         }
1312
1313         /**
1314          * @brief Counts the rows from a table satisfying the provided condition
1315          *
1316          * @param string $table Table name
1317          * @param array $condition array of fields for condition
1318          *
1319          * @return int
1320          *
1321          * Example:
1322          * $table = "item";
1323          *
1324          * $condition = ["uid" => 1, "network" => 'dspr'];
1325          * or:
1326          * $condition = ["`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr'];
1327          *
1328          * $count = dba::count($table, $condition);
1329          */
1330         public static function count($table, array $condition = [])
1331         {
1332                 if ($table == '') {
1333                         return false;
1334                 }
1335
1336                 $condition_string = self::buildCondition($condition);
1337
1338                 $sql = "SELECT COUNT(*) AS `count` FROM `".$table."`".$condition_string;
1339
1340                 $row = self::fetch_first($sql, $condition);
1341
1342                 return $row['count'];
1343         }
1344
1345         /**
1346          * @brief Returns the SQL condition string built from the provided condition array
1347          *
1348          * This function operates with two modes.
1349          * - Supplied with a filed/value associative array, it builds simple strict
1350          *   equality conditions linked by AND.
1351          * - Supplied with a flat list, the first element is the condition string and
1352          *   the following arguments are the values to be interpolated
1353          *
1354          * $condition = ["uid" => 1, "network" => 'dspr'];
1355          * or:
1356          * $condition = ["`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr'];
1357          *
1358          * In either case, the provided array is left with the parameters only
1359          *
1360          * @param array $condition
1361          * @return string
1362          */
1363         public static function buildCondition(array &$condition = [])
1364         {
1365                 $condition_string = '';
1366                 if (count($condition) > 0) {
1367                         reset($condition);
1368                         $first_key = key($condition);
1369                         if (is_int($first_key)) {
1370                                 $condition_string = " WHERE (" . array_shift($condition) . ")";
1371                         } else {
1372                                 $new_values = [];
1373                                 $condition_string = "";
1374                                 foreach ($condition as $field => $value) {
1375                                         if ($condition_string != "") {
1376                                                 $condition_string .= " AND ";
1377                                         }
1378                                         if (is_array($value)) {
1379                                                 /* Workaround for MySQL Bug #64791.
1380                                                  * Never mix data types inside any IN() condition.
1381                                                  * In case of mixed types, cast all as string.
1382                                                  * Logic needs to be consistent with dba::p() data types.
1383                                                  */
1384                                                 $is_int = false;
1385                                                 $is_alpha = false;
1386                                                 foreach ($value as $single_value) {
1387                                                         if (is_int($single_value)) {
1388                                                                 $is_int = true;
1389                                                         } else {
1390                                                                 $is_alpha = true;
1391                                                         }
1392                                                 }
1393
1394                                                 if ($is_int && $is_alpha) {
1395                                                         foreach ($value as &$ref) {
1396                                                                 if (is_int($ref)) {
1397                                                                         $ref = (string)$ref;
1398                                                                 }
1399                                                         }
1400                                                         unset($ref); //Prevent accidental re-use.
1401                                                 }
1402
1403                                                 $new_values = array_merge($new_values, array_values($value));
1404                                                 $placeholders = substr(str_repeat("?, ", count($value)), 0, -2);
1405                                                 $condition_string .= "`" . $field . "` IN (" . $placeholders . ")";
1406                                         } else {
1407                                                 $new_values[$field] = $value;
1408                                                 $condition_string .= "`" . $field . "` = ?";
1409                                         }
1410                                 }
1411                                 $condition_string = " WHERE (" . $condition_string . ")";
1412                                 $condition = $new_values;
1413                         }
1414                 }
1415
1416                 return $condition_string;
1417         }
1418
1419         /**
1420          * @brief Returns the SQL parameter string built from the provided parameter array
1421          *
1422          * @param array $params
1423          * @return string
1424          */
1425         public static function buildParameter(array $params = [])
1426         {
1427                 $order_string = '';
1428                 if (isset($params['order'])) {
1429                         $order_string = " ORDER BY ";
1430                         foreach ($params['order'] AS $fields => $order) {
1431                                 if (!is_int($fields)) {
1432                                         $order_string .= "`" . $fields . "` " . ($order ? "DESC" : "ASC") . ", ";
1433                                 } else {
1434                                         $order_string .= "`" . $order . "`, ";
1435                                 }
1436                         }
1437                         $order_string = substr($order_string, 0, -2);
1438                 }
1439
1440                 $limit_string = '';
1441                 if (isset($params['limit']) && is_int($params['limit'])) {
1442                         $limit_string = " LIMIT " . $params['limit'];
1443                 }
1444
1445                 if (isset($params['limit']) && is_array($params['limit'])) {
1446                         $limit_string = " LIMIT " . intval($params['limit'][0]) . ", " . intval($params['limit'][1]);
1447                 }
1448
1449                 return $order_string.$limit_string;
1450         }
1451
1452         /**
1453          * @brief Fills an array with data from a query
1454          *
1455          * @param object $stmt statement object
1456          * @return array Data array
1457          */
1458         public static function inArray($stmt, $do_close = true) {
1459                 if (is_bool($stmt)) {
1460                         return $stmt;
1461                 }
1462
1463                 $data = [];
1464                 while ($row = self::fetch($stmt)) {
1465                         $data[] = $row;
1466                 }
1467                 if ($do_close) {
1468                         self::close($stmt);
1469                 }
1470                 return $data;
1471         }
1472
1473         /**
1474          * @brief Returns the error number of the last query
1475          *
1476          * @return string Error number (0 if no error)
1477          */
1478         public static function errorNo() {
1479                 return self::$errorno;
1480         }
1481
1482         /**
1483          * @brief Returns the error message of the last query
1484          *
1485          * @return string Error message ('' if no error)
1486          */
1487         public static function errorMessage() {
1488                 return self::$error;
1489         }
1490
1491         /**
1492          * @brief Closes the current statement
1493          *
1494          * @param object $stmt statement object
1495          * @return boolean was the close successful?
1496          */
1497         public static function close($stmt) {
1498                 $a = get_app();
1499
1500                 $stamp1 = microtime(true);
1501
1502                 if (!is_object($stmt)) {
1503                         return false;
1504                 }
1505
1506                 switch (self::$driver) {
1507                         case 'pdo':
1508                                 $ret = $stmt->closeCursor();
1509                                 break;
1510                         case 'mysqli':
1511                                 // MySQLi offers both a mysqli_stmt and a mysqli_result class.
1512                                 // We should be careful not to assume the object type of $stmt
1513                                 // because dba::p() has been able to return both types.
1514                                 if ($stmt instanceof mysqli_stmt) {
1515                                         $stmt->free_result();
1516                                         $ret = $stmt->close();
1517                                 } elseif ($stmt instanceof mysqli_result) {
1518                                         $stmt->free();
1519                                         $ret = true;
1520                                 } else {
1521                                         $ret = false;
1522                                 }
1523                                 break;
1524                 }
1525
1526                 $a->save_timestamp($stamp1, 'database');
1527
1528                 return $ret;
1529         }
1530 }