Opens the *database* object associated with this ObjectId object, in the specified mode.

Returns a SmartPointer to the opened object if successful, otherwise a null SmartPointer. 

openMode must be one of the following: 

table Name Value Description OdDb::kForRead 0 Object is open for reading. OdDb::kForWrite 1 Object is open for reading and/or writing. OdDb::kForNotify 2 Object is open for notify.