正如uri2x所说,见SQL injection that gets around mysql_real_escape_string().

The best way to prevent SQL injection is to use prepared statements.它们将数据(您的参数)与指令(SQL查询字符串)分开,并且不会为数据留下任何污染查询结构的空间.准备好的声明解决了fundamental problems of application security之一.

对于无法使用预准备语句(例如LIMIT)的情况,为每个特定目的使用非常严格的白名单是保证安全性的唯一方法.

// This is a string literal whitelist
switch ($sortby) {
    case 'column_b':
    case 'col_c':
        // If it literally matches here,it's safe to use
        break;
    default:
        $sortby = 'rowid';
}

// Only numeric characters will pass through this part of the code thanks to type casting
$start = (int) $start;
$howmany = (int) $howmany;
if ($start < 0) {
    $start = 0;
}
if ($howmany < 1) {
    $howmany = 1;
}

// The actual query execution
$stmt = $db->PRepare(
    "SELECT * From table WHERE col = ? ORDER BY {$sortby} ASC LIMIT {$start},{$howmany}"
);
$stmt->execute(['value']);
$data = $stmt->fetchAll(PDO::FETCH_ASSOC);

我认为上面的代码不受sql注入的影响,即使在不起眼的边缘情况下也是如此.如果你正在使用MysqL,请确保你转动模拟准备.

$db->setattribute(\PDO::ATTR_EMULATE_PREPARES,false);