code: @Override
  	public Map<String, Object> first(final CaseFormat caseFormat) {
  		return findFirst(caseFormat).orElseThrow(() -> new DataNotFoundException("query result is empty."));
  	}
docs: {@inheritDoc}
  
  @see jp.co.future.uroborosql.fluent.SqlQuery#first(jp.co.future.uroborosql.utils.CaseFormat)