sparrow_fix.php

<?php

protected function parseCondition($field, $value = null, $join = '', $escape = true) {
        if (is_string($field)) {

            $operator = '';

            if (strpos($field, ' ') !== false) {
                list($field, $operator) = explode(' ', $field);
            }

            if (!empty($operator)) {
                switch ($operator) {
                    case '%':
                        $condition = ' LIKE ';
                        break;

                    case '!%':
                        $condition = ' NOT LIKE ';
                        break;

                    case '@':
                        $condition = ' IN ';
                        break;

                    case '!@':
                        $condition = ' NOT IN ';
                        break;

                    case '=':
                        $condition = ' IS ';
                        break;

                    case '!=':
                        $condition = ' IS NOT ';
                        break;

                    default:
                        $condition = $operator;
                }
            }
            else {
                if ($value === null) $condition = ' IS '; else $condition = '=';
            }

            if (empty($join)) { 
                $join = ($field{0} == '|') ? ' OR' : ' AND';
            }

            if (is_array($value)) {
                if (strpos($operator, '@') === false) $condition = ' IN ';
                $value = '('.implode(',', array_map(array($this, 'quote'), $value)).')';
            }
            else {
                $value = ($escape && !is_numeric($value)) ? $this->quote($value) : $value;
            }

            if ($value === null) $value = 'NULL';

            return $join.' '.str_replace('|', '', $field).$condition.$value;
        }
        else if (is_array($field)) {
            $str = '';
            foreach ($field as $key => $value) {
                $str .= $this->parseCondition($key, $value, $join, $escape);
                $join = '';
            }
            return $str;
        }
        else {
            throw new Exception('Invalid where condition.');
        }
    }

$db->from('users')->where('email', null)->many(); // IS NULL
$db->from('users')->where('email !=', null)->many(); // IS NOT NULL