Online PHP editor | output for sLmC9

<?php class sqli_protected_db { private $db; public function __construct() { // $this->db = new mysqli('localhost', 'username', 'password', 'database'); } public function query(String $sql, Array $parameters = [], Array $aliases = []) { if (!is_literal($sql)) { echo '[WRONG] '; } foreach ($aliases as $name => $value) { $sql = str_replace('{' . $name . '}', '`' . str_replace('`', '``', $value) . '`', $sql); } echo $sql . "\n\n"; // print_r(iterator_to_array($this->db->execute_query($sql, $parameters))); } } $db = new sqli_protected_db(); $id = ($_GET['id'] ?? chr(53)); // non-LiteralString '5' $order = ($_GET['order'] ?? chr(110)); // non-LiteralString 'n' $db->query('SELECT name FROM user WHERE id = ?', [$id]); // Correct $db->query('SELECT name FROM user WHERE id = ' . $id); // WRONG $db->query('SELECT name FROM user ORDER BY {o}', [], ['o' => $order]); // Correct $db->query('SELECT name FROM user ORDER BY ' . $order); // WRONG echo "-----\n\n"; class query_builder { public function where(String $column, ?String $operator = null, $value = null) { if (!is_literal($column) || (!is_literal($operator) && $operator !== null)) { echo '[WRONG] '; } echo $column . ($operator === null ? '' : ' ' . $operator) . ($value === null ? '' : ' ?') . "\n\n"; } } $qb = new query_builder(); $name = ($_GET['name'] ?? chr(110)); // non-LiteralString 'n' $field = ($_GET['field'] ?? chr(102)); // non-LiteralString 'f' $value = ($_GET['value'] ?? chr(118)); // non-LiteralString 'v' $qb->where('CONCAT(name_first, " ", name_last)', 'LIKE', $name); // Correct $qb->where('CONCAT(name_first, " ", name_last) LIKE "' . $name . '"'); // WRONG $qb->where('some_value IS NULL'); // Correct $qb->where($field, '=', $value); // WRONG echo "-----\n\n"; // https://github.com/doctrine/orm/blob/2.12.x/lib/Doctrine/ORM/Query/Expr/Func.php class Func { protected $name; protected $arguments; public function __construct($name, $arguments) { $this->name = $name; $this->arguments = $arguments; } public function __toString() { return $this->name . '(' . implode(', ', $this->arguments) . ')'; } } function check_func(Func $func) { $sql = (string) $func; if (!is_literal($sql)) { echo '[WRONG] '; } echo $sql . "\n\n"; } $func = ($_GET['func'] ?? chr(102)); // non-LiteralString 'f' $value = ($_GET['value'] ?? chr(118)); // non-LiteralString 'v' check_func(new Func('MIN', ['field1', 'field2'])); // Correct check_func(new Func($func, ['field1', 'field2'])); // WRONG check_func(new Func('MIN', ['field1', $value])); // WRONG ?>