Is there any possibility to iterate or loop through a "User Defined Variables" - set like it's possible with a CSV data set (WHILE-COUNTER-CSV Data Set Config)?

I want to fire a JDBC request (Select Statement) **for each** variable contained in the "User Defined Variables" - Set. It works fine with a CSV file, but i can't figure out how I can loop through a variables set. Is that even possible? I have various scenarios, where I want to loop through a "User Defined Variables" - set.