code: private void deleteChildEntities(Table childTable, Field keyField, String keyValue) throws SQLException {
          String childTableName = String.join(".", tablePrefix, childTable.name);
          PreparedStatement deleteStatement = getUpdateReferencesStatement(SqlMethod.DELETE, childTableName, keyField, keyValue, null);
          LOG.info(deleteStatement.toString());
          int result = deleteStatement.executeUpdate();
          LOG.info("Deleted {} {}", result, childTable.name);
          // FIXME: are there cases when an update should not return zero?
          //   if (result == 0) throw new SQLException("No stop times found for trip ID");
      }
docs: Delete existing sub-entities for given key value for when an update to the parent entity is made (i.e., the parent
  entity is not being newly created). Examples of sub-entities include stop times for trips, pattern stops for a
  pattern, or shape points (for a pattern in our model).