Connection::query

public Connection::query($query, array $args = array(), $options = array())

public function query($query, array $args = array(), $options = array()) {
  // Use default values if not already set.
  $options += $this->defaultOptions();

  try {
    // We allow either a pre-bound statement object or a literal string.
    // In either case, we want to end up with an executed statement object,
    // which we pass to PDOStatement::execute.
    if ($query instanceof StatementInterface) {
      $stmt = $query;
      $stmt->execute(NULL, $options);
    }
    else {
      $this->expandArguments($query, $args);
      // To protect against SQL injection, Drupal only supports executing one
      // statement at a time.  Thus, the presence of a SQL delimiter (the
      // semicolon) is not allowed unless the option is set.  Allowing
      // semicolons should only be needed for special cases like defining a
      // function or stored procedure in SQL. Trim any trailing delimiter to
      // minimize false positives.
      $query = rtrim($query, ";  \t\n\r\0\x0B");
      if (strpos($query, ';') !== FALSE && empty($options['allow_delimiter_in_query'])) {
        throw new \InvalidArgumentException('; is not supported in SQL strings. Use only one statement at a time.');
      }
      $stmt = $this->prepareQuery($query);
      $stmt->execute($args, $options);
    }

    // Depending on the type of query we may need to return a different value.
    // See DatabaseConnection::defaultOptions() for a description of each
    // value.
    switch ($options['return']) {
      case Database::RETURN_STATEMENT:
        return $stmt;
      case Database::RETURN_AFFECTED:
        $stmt->allowRowCount = TRUE;
        return $stmt->rowCount();
      case Database::RETURN_INSERT_ID:
        $sequence_name = isset($options['sequence_name']) ? $options['sequence_name'] : NULL;
        return $this->connection->lastInsertId($sequence_name);
      case Database::RETURN_NULL:
        return NULL;
      default:
        throw new \PDOException('Invalid return directive: ' . $options['return']);
    }
  }
  catch (\PDOException $e) {
    // Most database drivers will return NULL here, but some of them
    // (e.g. the SQLite driver) may need to re-run the query, so the return
    // value will be the same as for static::query().
    return $this->handleQueryException($e, $query, $args, $options);
  }
}