code: def namedb_get_name_preorder( db, preorder_hash, current_block ):
      
  
      select_query = "SELECT * FROM preorders WHERE preorder_hash = ? AND op = ? AND block_number < ?;"
      args = (preorder_hash, NAME_PREORDER, current_block + NAME_PREORDER_EXPIRE)
  
      cur = db.cursor()
      preorder_rows = namedb_query_execute( cur, select_query, args )
      
      preorder_row = preorder_rows.fetchone()
      if preorder_row is None:
          # no such preorder 
          return None 
  
      preorder_rec = {}
      preorder_rec.update( preorder_row )
  
      unexpired_query, unexpired_args = namedb_select_where_unexpired_names( current_block )
  
      # make sure that the name doesn't already exist 
      select_query = "SELECT name_records.preorder_hash " + \
                     "FROM name_records JOIN namespaces ON name_records.namespace_id = namespaces.namespace_id " + \
                     "WHERE name_records.preorder_hash = ? AND " + \
                     unexpired_query + ";"
  
      args = (preorder_hash,) + unexpired_args
      
      cur = db.cursor()
      nm_rows = namedb_query_execute( cur, select_query, args )
  
      nm_row = nm_rows.fetchone()
      if nm_row is not None:
          # name with this preorder exists 
          return None 
  
      return preorder_rec
docs: Get a (singular) name preorder record outstanding at the given block, given the preorder hash.
      NOTE: returns expired preorders.
      
      Return the preorder record on success.
      Return None if not found.