Question

我有一组看起来如下的表

 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

如何展平表格以使结果看起来像：

 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equipent.equipmeintID
fk_parentGroupID链接到group.groupID

valueGroup遵循相同的概念：

fk_groupID链接到group.groupID
fk_parentValueId指向valueID

对于groupGroup和valueGroup表条目，条目可能有也可能没有递归条目。组表条目将始终至少有一个与组的最后一个祖先相关联的valueGroup条目;但可能不止一个。

我一直在关注https://dba.stackexchange.com/questions/7147/find-highest-level-of-a-hierarchical-field-with-vs-without-ctes/7161#7161并能够正确显示标签，但我无法进一步了解。

Answer 1

如果您的表具有最大深度数，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，需要每个递归值的存储过程/函数，因为不可能以任何其他方式获取具有未知深度的递归数据。要确定，请使用谷歌。所以这就是你的存储函数的样子：

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

然后你可以简单地做一个这样的查询：

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

结果与您的结果略有不同：

|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。

Answer 2

SELECT e.equipmentID,name,
 IF(T2.label IS NULL,T1.label,
 CONCAT(T1.label,', ',T2.label,', ',T3.label,', ',T4.label)) as labels,
 v.value
FROM equipment e
INNER JOIN `group` T1 ON T1.fk_equipmentID = e.equipmentID AND T1.fk_parentGroupID IS NULL
LEFT JOIN `group` T2 ON T2.fk_parentGroupID = T1.groupID AND T2.fk_equipmentID = T1.fk_equipmentID
LEFT JOIN `group` T3 ON T3.fk_parentGroupID = T2.groupID AND T3.fk_equipmentID = T1.fk_equipmentID
LEFT JOIN `group` T4 ON T4.fk_parentGroupID = T3.groupID AND T4.fk_equipmentID = T1.fk_equipmentID
INNER JOIN valueGroup vg1 ON (vg1.fk_groupID = T4.groupID) OR (vg1.fk_groupID = T1.groupID)
LEFT JOIN valueGroup vg2 ON (vg2.fk_parentValueID = vg1.valueID)
INNER JOIN `values` v ON (v.fk_valueID = vg1.valueID) OR (v.fk_valueID = vg2.valueID)

sqlFiddle

MySQL flatten 2加入了递归表

2 个答案: