public void deleteAllCommentsByBoardId(final Long boardId) {
        String sql = "DELETE FROM comment WHERE board_id = :boardId";

        namedParameterJdbcTemplate.update(sql, new MapSqlParameterSource("boardId", boardId));
    }
@Test
    void 게시글_id에_해당되는_것을_모두_지운다() {
        // given
        Comment savedComment = commentJpaRepository.save(댓글_생성());

        // when
        commentJdbcRepository.deleteAllCommentsByBoardId(savedComment.getBoardId());

        // then
        Optional<Comment> result = commentJpaRepository.findById(1L);
        assertThat(result).isEmpty();
    }