Question

这是我的表和示例数据。

CREATE TABLE `sections` (
  `section_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `parent_section_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`section_id`)
);

INSERT INTO `sections` (`section_id`, `name`, `parent_section_id`) VALUES
(1, 'City', NULL),
(2, 'Supplements', 4),
(3, 'News', 5),
(4, 'Sunday', 2),
(5, 'Monday', 2),
(6, 'Tuesday', 2),
(7, 'Wednesday', 2),
(8, 'Thursday', 2),
(9, 'Friday', 2),
(10, 'Saturday', 2),
(11, 'Home', 4),
(12, 'Games', 4),
(13, 'Sites', 5),
(14, 'Sports', 5),
(15, 'Cyber Space', 6);

parent_section_id是引用同一个表中section_id的外键，如果它不属于任何其他部分，则可以为null。

如何获得以下输出我尝试过使用group_concat函数，但它没有给出确切的结果。 parent_section_id指向同一个表中的id。我应该使用任何其他列来实现以下输出，还是使用其他表来跟踪包含子节的章节。请帮我解决这个问题或建议任何其他方法

id, Name, SubSections
----------------------
1, 'City', null
2, 'Supplements', 'Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday'
3, 'News', null
4, 'Sunday', 'Homes,Games'
5, 'Monday','Sites,Sports'
6, 'Tuesday', 'Cyber Space'
7, 'Wednesday', null
8, 'Thursday', null
9, 'Friday', null
10, 'Saturday', null
11, 'Home', null
12, 'Games', null
13, 'Site', null
14, 'Sports', null
15, 'Cyber Space',null

这是sql小提琴链接http://sqlfiddle.com/#!9/e9767/2

最终查询

select s1.section_id, s1.name, group_concat(s2.name) as subsections,
(select name from sections where section_id = s1.parent_section_id) as 'parentname'
from sections s1
left join sections s2 on s1.section_id = s2.parent_section_id
group by s1.section_id;

Answer 1

您可以使用section_id = parent_section_id上的（左）自加入来获得您想要的结果，如下所示：

select s1.section_id, s1.name, group_concat(s2.name) as subsections
from sections s1
left join sections s2 on s1.section_id = s2.parent_section_id
group by s1.section_id;

Sample SQL Fiddle

使用group_concat和表中的自引用id的Mysql查询

1 个答案: