我有一组如下所示的表格
equipment
_____________________________________________________
equipmentID | name
_____________________________________________________
1 widgetA
2 widgetB
group
_____________________________________________________
fk_equipmentID | groupId | fk_parentGroupID | label
_____________________________________________________
1 1 null Dimensions
1 2 1 Overall
1 3 2 External
1 4 3 length
1 5 3 width
1 6 3 height
1 7 null Dimensions
1 8 7 Overall
1 9 8 Internal
1 10 9 length
1 11 9 width
1 12 9 height
1 13 null color
valueGroup
_____________________________________________________
fk_groupID | valueID | fk_parentVlaueID
_____________________________________________________
4 1 null
null 2 1
null 3 1
5 4 null
6 5 null
10 6 null
null 7 6
11 8 null
12 9 null
13 10 null
values
_____________________________________________________
fk_valueID | id | value
_____________________________________________________
2 1 5in
3 2 12.7mm
5 3 1 meter
6 4 0.5m
7 5 2in
8 6 10in
9 7 .25m
10 8 blue
如何展平表格以获得如下所示的结果:
equipmentID | name | labels | value
_______________________________________________________________________
1 widgetA Dimensions, External, Overall, length 5in
1 widgetA Dimensions, External, Overall, length 12.7mm
1 widgetA Dimensions, External, Overall, width 1 meter
1 widgetA Dimensions, External, Overall, height 0.5m
1 widgetA Dimensions, External, Internal, length 2in
1 widgetA Dimensions, External, Internal, width 10in
1 widgetA Dimensions, External, Internal, height .25m
1 widgetA color blue
表组有 2 个外键:
- fk_equipmentID 链接到 Equipment.equipmeintID
- fk_parentGroupID 链接到 group.groupID
valueGroup 也遵循相同的概念:
- fk_groupID 链接到 group.groupID
- fk_parentValueId 链接到 valueID
对于组和值组表,条目可能有也可能没有递归条目。组表条目将始终具有至少一个与该组的最后祖先相关联的 valueGroup 条目;但可能有不止一个。
我一直在看https://dba.stackexchange.com/questions/7147/find-highest-level-of-a-hierarchical-field-with-vs-without-ctes/7161#7161并能够使标签正确显示,但我无法取得进一步的进展。
最佳答案
如果您的表有最大深度数并且您可以保证永远不会超过它,请使用@Wanderer 的解决方案。否则,您需要每个递归值一个存储过程/函数,因为不可能以任何其他方式获取深度未知的递归数据。为了确定,请使用谷歌。 因此,您的存储函数如下所示:
CREATE DEFINER=`root`@`localhost` FUNCTION `getRootValueGroup`(childCId INT, `value` BOOLEAN) RETURNS int(11)
READS SQL DATA
DETERMINISTIC
SQL SECURITY INVOKER
BEGIN
DECLARE parentCId INT;
DECLARE currentCId INT;
SET parentCId = childCId;
WHILE !(parentCId IS NULL) DO
SET currentCId = parentCId;
IF `value` THEN
SELECT fk_parentGroupID FROM `group` WHERE groupId = currentCId INTO parentCId;
ELSE
SELECT fk_parentVlaueID FROM valueGroup WHERE valueID = currentCId INTO parentCId;
END IF;
END WHILE;
RETURN currentCId;
END
和
CREATE DEFINER=`root`@`localhost` FUNCTION `getGroupList`(childCId INT) RETURNS VARCHAR(256)
READS SQL DATA
DETERMINISTIC
SQL SECURITY INVOKER
BEGIN
DECLARE parentCId INT;
DECLARE currentCId INT;
DECLARE labels VARCHAR(256);
DECLARE label VARCHAR(32);
SET labels = '';
SET parentCId = childCId;
WHILE !(parentCId IS NULL) DO
SET currentCId = parentCId;
SELECT fk_parentGroupID, g.label FROM `group` g WHERE groupId = currentCId INTO parentCId, label;
SET labels = CONCAT(label, ', ', labels);
END WHILE;
SET labels = TRIM(TRAILING ',' FROM TRIM(TRAILING ' ' FROM labels));
RETURN labels;
END
然后你可以简单地执行这样的查询:
SELECT e.equipmentID as equipmentID, e.name as name, getGroupList(vg.fk_groupID) as labels, v.`value` as `value`
FROM `values` v
JOIN valueGroup vg ON vg.valueID = getRootValueGroup(v.fk_valueID, FALSE)
JOIN `group` g ON g.groupID = getRootValueGroup(vg.fk_groupID, TRUE)
JOIN `equipment` e ON e.equipmentID = g.fk_equipmentID
结果看起来与您的有点不同:
|1|widgetA|Dimensions, Overall, External, length|5in
|1|widgetA|Dimensions, Overall, External, length|12.7mm
|1|widgetA|Dimensions, Overall, External, height|1 meter
|1|widgetA|Dimensions, Overall, Internal, length|0.5m
|1|widgetA|Dimensions, Overall, Internal, length|2in
|1|widgetA|Dimensions, Overall, Internal, width |10in
|1|widgetA|Dimensions, Overall, Internal, height|0.25m
|1|widgetA|color |blue
但我无法想象你怎么可能得到你在问题中显示的结果。
关于MySQL压平2个连接的递归表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21191058/