Question:
how can i join vendor table with ldb PNP in a query
Answer:
I don't know wich is the vendor table but if you want to add tables to a query you must first add the table on the infosets with SQ02 (or SQ01, I will never remember it).
on the left side you have all the Infotypes and you should add the table with the right button on a infotype or by menu...
You will sure do that, naturally... you must have fields to join (it does that the fields join automatically if there are fields to join).
good luck