Material not available, directly create PO

WHEN AM CREATING SALES ORDER, IF MATERIAL IS NOT AVAILABLE THEN IT SHOULD DIRECTLY CONVERT IT TO PURCHASE ORDER... HOW TO DO IT...

i.e in SALES ORDER ITEM CATEGORY SHOULD TO BE CHANGE DIRECTLY FROM TAN TO TAS..... AND PURCHASE ORDER SHOULD BE CREATED AUTOMATICALLY...

GUYS HELP ME OUT  HOW TO DO IT.....

THANKS IN ADVANCE.

Message was edited by: Jyoti Prakash

Its totally UNPROFESSIONAL to post discussion & it's tittle in all CAPS.

Posting any post in such manner is like SHOUTING.

So, don't do that in future.