Adobe doesn't offer anything like that as out of the box, but it is still possible to achieve it.
I'm a bit confused about the "The quiz is a flash swf embed in a html-file". Is this an actual Flash file or is it the swf output from Captivate?
If it's a Flash file then just implement what ever communication you want in the Flash file itself and tie in the relevant PHP scripts and database info.
If it's a Captivate swf then your options are a bit more restricted:
Option 1: If you can use Flash you could create a Flash file that is imported into the Captivate project that contains the communication with the database. You can retrieve the relevant data from Captivate by using the system variables.
Option 2: Use the "email hack" procedure described here and modify it to work with PHP/MySQL instead. http://www.adobe.com/devnet/captivate/articles/store_cpresults.html
it is "If it's a Captivate swf then your options are a bit more restricted:"
and I would like to take option 1.
I know how to create a Flash and how to read a swf into a flash BUT,
"using the system variables." I need to know the variable-names.
In my example we have one question and the user take answer 1.
How is the variablename of the answer of question x?
What, if the user can choose more than one answer?
Whalt, if I have more then one questions.
Is there a referent in the www ?
Take a look at these two links:
This one gives you "all" the available variables in Captivate 4.
This one is a tutorial on how to save the users quiz selections in a user defined variable in Captivate. Basically you could use that principle to get the data into your flash file.