找到一個樹形結構表

Question

我有一個這樣的表結構的共同祖先（其實有更多的層次）：

------------------------------------------ 
|region1|region2|region3|region4|postcode| 
|-------|-------|-------|-------|--------| 
|a  |x  |i  |  |1  | 
|a  |y  |i  |  |2  | 
|a  |y  |j  |  |2  | 
|a  |z  |k  |  |3  | 
|b  |u  |m  |  |4  | 
|b  |  |n  |  |4  | 
|c  |  |  |  |5  | 
|c  |q  |  |  |6  | 
------------------------------------------ 

因此，例如，a => x => i和a => y => i有不同的地方，但兩者在相同的區域1 a。

我想知道每個郵政編碼可以覆蓋哪個區域。

例如，代碼2涵蓋區域a => y => i和a => y => j，因此這些共同的祖先是a => y。

這裏是關於例如運行查詢所需的輸出：

------------------------------------------ 
|postcode|region1|region2|region3|region4| 
|--------|-------|-------|-------|-------| 
|1  |a  |x  |i  |  | 
|2  |a  |y  |  |  | 
|3  |a  |z  |k  |  | 
|4  |b  |  |  |  | 
|5  |c  |  |  |  | 
|6  |c  |q  |  |  | 
------------------------------------------ 

我真的不知道如何攻擊這個問題。我想通過郵編分區，但這仍然留下找到每個分區內共同的祖先的問題...

Answer 1

這是一個非常混亂的解決方案，但它似乎給出了正確的答案。毫無疑問，需要相當多的工作來滿足您的實際需求，但也許這可能會幫助您指引某種方向！

-- Setup a test table 

DECLARE @tbl AS TABLE(R1 NVARCHAR(10), R2 NVARCHAR(10), R3 NVARCHAR(10), R4 NVARCHAR(10), PC NVARCHAR(10)); 

INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('a','x','i',NULL,'1'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('a','y','i',NULL,'2'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('a','y','j',NULL,'2'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('a','z','k',NULL,'3'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('b','u','m',NULL,'4'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('b',NULL,'n',NULL,'4'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('c',NULL,NULL,NULL,'5'); 
INSERT INTO @tbl(R1,R2,R3,R4,PC) VALUES ('c','q',NULL,NULL,'6'); 

-- Calculate the result: 

SELECT 
    PC, 
    CASE WHEN LVL1 = 1 THEN R1 ELSE NULL END AS R1, 
    CASE WHEN LVL2 = 1 THEN R2 ELSE NULL END AS R2, 
    CASE WHEN LVL3 = 1 THEN R3 ELSE NULL END AS R3, 
    CASE WHEN LVL4 = 1 THEN R4 ELSE NULL END AS R4 
FROM 
(
    SELECT 
     PC, 
     MAX(R1) AS R1, 
     MAX(R2) AS R2, 
     MAX(R3) AS R3, 
     MAX(R4) AS R4, 
     COUNT(DISTINCT ISNULL(R1,'.')) AS LVL1, 
     COUNT(DISTINCT ISNULL(R1,'.') + ISNULL(R2,'.')) AS LVL2, 
     COUNT(DISTINCT ISNULL(R1,'.') + ISNULL(R2,'.') + ISNULL(R3,'.')) AS LVL3, 
     COUNT(DISTINCT ISNULL(R1,'.') + ISNULL(R2,'.') + ISNULL(R3,'.') + ISNULL(R4,'.')) AS LVL4 
    FROM @tbl 
    GROUP BY PC 
) A 

最終結果與問題中的表格匹配。

Answer 2

這個問題，而吸引了我，我想出了一個替代方案，這可能對您有用：

-- Setup test table 
DECLARE @InputTable TABLE (region1 varchar(2), region2 varchar(2), region3 varchar(2), region4 varchar(2), postcode varchar(2)) 

INSERT INTO @InputTable (region1, region2, region3, region4, postcode) 
      SELECT 'a','x','i',null,'1' 
UNION ALL SELECT 'a','y','i',NULL,'2' 
UNION ALL SELECT 'a','y','j',NULL,'2' 
UNION ALL SELECT 'a','z','k',NULL,'3' 
UNION ALL SELECT 'b','u','m',NULL,'4' 
UNION ALL SELECT 'b',NULL,'n',NULL,'4' 
UNION ALL SELECT 'c',NULL,NULL,NULL,'5' 
UNION ALL SELECT 'c','q',NULL,NULL,'6' 

-- Find the common ancestors 
;with totals as (
    select postcode, count(*) as postcodeCount from @InputTable group by postcode 
) 
, region4group as (
    select postcode, region1, region2, region3, region4 from @InputTable in1 
    group by postcode, region1, region2, region3, region4 having count(*)=(select postCodeCount from totals where totals.postcode=in1.postcode) 
) 
, region3group as (
    select * from region4group 
    union 
    select in1.postcode, in1.region1, in1.region2, in1.region3, null from @InputTable in1 
    left outer join region4group on region4group.postcode=in1.postcode 
    where region4group.postcode is null 
    group by in1.postcode, in1.region1, in1.region2, in1.region3 
    having count(*)=(select postCodeCount from totals where totals.postcode=in1.postcode) 
) 
, region2group as (
    select * from region3group 
    union 
    select in1.postcode, in1.region1, in1.region2, null, null from @InputTable in1 
    left outer join region3group on region3group.postcode=in1.postcode 
    where region3group.postcode is null 
    group by in1.postcode, in1.region1, in1.region2 
    having count(*)=(select postCodeCount from totals where totals.postcode=in1.postcode) 
) 
, commonancestors as (
    select * from region2group 
    union 
    select in1.postcode, in1.region1, null, null, null from @InputTable in1 
    left outer join region2group on region2group.postcode=in1.postcode 
    where region2group.postcode is null 
    group by in1.postcode, in1.region1 
    having count(*)=(select postCodeCount from totals where totals.postcode=in1.postcode) 
) 
select * from commonancestors