SQL link between 2D and WTPART

Hello,

Does somebody know what the link in SQL is between a 2D drawing and a WTPart? I can't find it.

I tried this:

select epmdocumentmaster.documentnumber, wtpartnumber
from epmbuildrule,wtpart,wtpartmaster,epmdocument,epmdocumentmaster where
epmdocument.branchiditerationinfo = epmbuildrule.branchida3a5 and
epmdocument.latestiterationinfo='1' and
epmdocumentmaster.ida3a6 = epmdocument.ida3masterreference and
wtpart.branchiditerationinfo = epmbuildrule.branchida3b5 and 
wtpart.latestiterationinfo='1' and
wtpartmaster.ida2a2 = wtpart.ida3masterreference and
wtpartmaster.wtpartnumber='7033571';

With this I get an empty result, so something is wrong.

Thanks in advance