我有一个旧表,它使用Parent/Child结构及其ID,我需要先按父表的Names排序,然后按子表(Parents have null
parent_id)排序。
我已经能够使用下面显示的SQL让它按子名称排序,但无法让它对主节点执行相同的操作(Cables
应该在Cameras
之前)。
SELECT a.id, a.parent_id,a.name
FROM `equipment` AS a
ORDER BY COALESCE(a.parent_id, a.id), a.parent_id IS NOT NULL, a.name
我已经修补了各种订单的可能性,但无法获得我需要的类型。任何指导都是值得感谢的。
表行
id | parent_id | name
--------------------------------
1 | null | Cameras
2 | 1 | HandyCam 2000 5-50
3 | 1 | Netgear 360
4 | null | Tripods
5 | 4 | Deluxe Tripod
6 | null | Lighting
7 | 6 | Light Diffuser
10 | 6 | Really bright bulbs
11 | 1 | 16MM Handheld
12 | 6 | Big Lightbulb assembly
13 | 4 | HandyCam Stand
16 | 4 | My New Tripod
181 | null | Cables
排序的结果(仅对子项排序)
id | parent_id | name
--------------------------------
1 | null | Cameras
11 | 1 | 16MM Handheld
2 | 1 | HandyCam 2000 5-50
3 | 1 | Netgear 360
4 | null | Tripods
5 | 4 | Deluxe Tripod
13 | 4 | HandyCam Stand
16 | 4 | My New Tripod
6 | null | Lighting
10 | 6 | Really bright bulbs
12 | 6 | Big Lightbulb assembly
7 | 6 | Light Diffuser
181 | null | Cables
发布于 2018-07-19 06:46:08
您需要将表与自身连接起来,这样才能获得每个子级的父级的名称,并在排序中使用该名称,而不是使用COALESCE(a.parent_id, a.id)
SELECT a.id, a.parent_id,IF(a.parent_id IS NULL, a.name, CONCAT(' ', a.name)) AS name
FROM `studio_tvs_equipment` AS a
JOIN studio_tvs_equipment AS b ON IF(a.parent_id IS NULL, a.id = b.id, b.id = a.parent_id)
ORDER BY IF(a.parent_id IS NULL, a.name, b.name), a.parent_id IS NOT NULL, a.name
https://stackoverflow.com/questions/51411919
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