docs: def create_tables(self):
          """
          create tables in database (if they don't already exist)
          """
          cdir = os.path.dirname( os.path.realpath(__file__) )
          
          # table schemas -------------------------------------
          schema = os.path.join(cdir,"data","partsmaster.sql")
          if self.debug:
              print(self.hdr,"parts master schema is ",schema)
          
          self.populate(schema)
          
          schema = os.path.join(cdir,"data","approvedmfg.sql")
          if self.debug:
              print(self.hdr,"approved mfg list schema is ",schema)
          
          self.populate(schema)
          
          schema = os.path.join(cdir,"data","attachment.sql")
          if self.debug:
              print(self.hdr,"attachment schema is ",schema)
          
          self.populate(schema)
  
          schema = os.path.join(cdir,"data","bom.sql")
          if self.debug:
              print(self.hdr,"bill of materials schema is ",schema)
          
          self.populate(schema)
          
          return