Purchase Requsition

Hello All,

do you have any experience, how to link Purchase Requsition Number to Asset Card Number? From my point of view, it would be the best to create function module, but I cannot find the key how to join data from tables EBAN (Purchase Requsition) and ANKA (Asset Card ??? I am not 100% sure). I am working with SAP few weeks, so each idea will be very helpful.

Best Regards,
Dimitrij