Oracle SQL 来自单个 table 的 3 级结构

Question

我有一个 table STRUCTURE，其中在查询时包含以下数据：

SELECT *
FROM STRUCTURE
WHERE structure_id = 'LOCA'

structure_id    name_value  description     level_no    item_above  structure_item_type_db  Level_id    level_description
LOCA            3000        North           4           300         1                       4           Area
LOCA            827         North A         4           3000        2                       4           Area
LOCA            828         North 1         4           3000        2                       4           Area
LOCA            829         North 2         4           3000        2                       4           Area
LOCA            830         North 3         4           3000        2                       4           Area
LOCA            300         North & South   3           LOCA        1                       3           Area Group
LOCA            3010        North Other     4           300         1                       4           Area
LOCA            879         North Other     4           3010        2                       4           Area

我有此代码可获得 2 级（描述和 Area_Group），但我无法获得第 3 级。

WITH CTE(NAME_VALUE, ITEM_ABOVE, DESCRIPTION, Area_Group) AS 
(
   SELECT NAME_VALUE, ITEM_ABOVE, DESCRIPTION, DESCRIPTION AS Area_Group
   FROM STRUCTURE
   WHERE ITEM_ABOVE = 'LOCA' AND Structure_id = 'LOCA'
   UNION ALL
   SELECT t1.NAME_VALUE, t1.ITEM_ABOVE, t1.DESCRIPTION, t2.Area_Group
   FROM STRUCTURE t1
   JOIN CTE t2 ON t1.ITEM_ABOVE = t2.NAME_VALUE
   WHERE  Structure_id = 'LOCA'
)
SELECT DESCRIPTION, Area_Group
FROM CTE

给我：

description     Area_Group
North           North & South
North A         North & South
North 1         North & South
North 2         North & South
North 3         North & South
North & South   North & South
North Other     North & South
North Other     North & South

我想输出数据（WHERE structure_id = 'LOCA' 是必需的，因为在这种情况下还有其他未使用的结构）看起来像这样：

description     Area_Group      Area
North           North & South   North
North A         North & South   North
North 1         North & South   North
North 2         North & South   North
North 3         North & South   North
North & South   North & South   North
North Other     North & South   North Other
North Other     North & South   North Other

所以如果我们把结构想象成一个树结构...

Area_Group - North & South
     └ Area - North
         └ description - North A
           description - North 1
           description - North 2
           description - North 3
     └ Area - North Other
         └ description - North Other

Answer 1

这应该有所帮助，两个自连接和 CASE WHEN 语句：

WITH
  sa AS (SELECT * 
         FROM structure 
         WHERE structure_id = 'LOCA'),
  sb AS (SELECT s1.description, s1.name_value, s1.level_id,
         CASE WHEN s1.structure_item_type_db = 1
              THEN s1.description 
              ELSE s2.description
         END area,
         CASE WHEN s1.structure_item_type_db = 1
              THEN s1.item_above 
              ELSE s2.item_above
         END item_above
         FROM sa s1 
         LEFT JOIN sa s2 ON s2.name_value = s1.item_above)
         SELECT s1.description, 
         CASE WHEN s1.level_id = 3 
              THEN s1.description 
              ELSE s2.description 
         END area_group, s1.area
         FROM sb s1 
         LEFT JOIN sb s2 ON s2.name_value = s1.item_above

^{SQL Fiddle demo}

在您的数据中，第 6 行 item_above 的值为 3500，并且没有包含此类 name_value 的行，因此 left join 在此不附加任何内容。添加的列 ID 仅用于展示目的。

输出：

   DESCRIPTION     AREA_GROUP      AREA
 --------------- --------------- ---------------
   North           North & South   North
   North A         North & South   North
   North 1         North & South   North
   North 2         North & South   North
   North 3         North & South   North         
   North & South   North & South   North & South
   North Other     North & South   North Other
   North Other     North & South   North Other

Oracle SQL 来自单个 table 的 3 级结构

Oracle SQL 3 Level Structure from a single table

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oracle

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