code: def namedb_get_namespace_preorder( db, namespace_preorder_hash, current_block ):
      
  
      cur = db.cursor()
      select_query = "SELECT * FROM preorders WHERE preorder_hash = ? AND op = ? AND block_number < ?;"
      args = (namespace_preorder_hash, NAMESPACE_PREORDER, current_block + NAMESPACE_PREORDER_EXPIRE)
      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 )
  
      # make sure that the namespace doesn't already exist 
      cur = db.cursor()
      select_query = "SELECT preorder_hash FROM namespaces WHERE preorder_hash = ? AND ((op = ?) OR (op = ? AND reveal_block < ?));"
      args = (namespace_preorder_hash, NAMESPACE_READY, NAMESPACE_REVEAL, current_block + NAMESPACE_REVEAL_EXPIRE)
      ns_rows = namedb_query_execute( cur, select_query, args )
  
      ns_row = ns_rows.fetchone()
      if ns_row is not None:
          # exists
          return None 
  
      return preorder_rec
docs: Get a namespace preorder, given its hash.
  
      Return the preorder record on success.
      Return None if not found, or if it expired, or if the namespace was revealed or readied.