Youtube not showing dropdown menu (where you can switch to dark mode, etc...)

To enable drop down on your name after you sign in (top, right), go to https://www.youtube.com/new and enable the new youtube experience

After the page loads, you can switch to dark theme etc

Query a XML string for a specific field value in oracle SQL

1	select extractvalue(XMLTYPE(inputxml), '/ROOT/DATA/ELEMENT') "Value" from MYTABLE

Where inputxml is a varchar2 column (storing xml as a string)
if you are storing data in a Xml datatype, you can remove XMLTYPE() function call

How to debug an aspx file with Visual Studio in IIS, that is not part of a project (or catch website exceptions with Visual Studio)

You have a file in IIS, you want to debug/step through

Open new instance of Visual studio (you may want to run it as Administrator)
File -> Open -> Web Site
In the left side, select Local IIS
Expand and locate the IIS Website your aspx file is part of

Any exception on this site will be caught now by VS