Question

这是我的情景：我有两个表A，B（为了这个问题是相同的）：

表X（PK）

ID 
1
2

表A：

ID FKID Value Sort
1  1    a     1
2  1    aa    2
3  1    aaa   3
4  2    aaaa  1
5  2    aaaaa 2

表B：

ID FKID Value Sort
1  1    b     1
2  1    bb    2
3  2    bbb   1
4  2    bbbb  2
5  2    bbbbb 3

期望的输出：

FKID ValueA ValueB Sort
1    a      b      1
1    aa     bb     2
1    aaa    (null) 3
2    aaaa   bbb    1
2    aaaaa  bbbb   2
2    (null) bbbbb  3

所以记录 1 有3-As和2-Bs，而记录 2 的2-As和3-B都与Sort整数列很好地配对。 / p>

我目前的解决方案涉及与Numbers表交叉加入。它有效，但由于这些表中的项目数量是无限的，我的数字表是大的（应用程序是非理性的，但实际上，我可以将它限制为1000）。

我还可以使用函数和子查询生成数字表，但性能感觉更差（我知道，我需要测试它！）。

所以我在想：也许有更好的方法来解决这个问题？我希望在我现在和合并桌子之间有一个愉快的媒介。

还有一件事：我坚持使用SQL Server 2000 ：P。

更新：在上面添加了PK表，以阐明我在寻找什么。我还修复了所需的输出。对于那个很抱歉。

更新：完整解决方案：

DECLARE @X AS TABLE (ID INT)
DECLARE @A AS TABLE (ID INT, FKID INT, Value VARCHAR(10), Sort INT)
DECLARE @B AS TABLE (ID INT, FKID INT, Value VARCHAR(10), Sort INT)

INSERT INTO @X (ID) VALUES (1)
INSERT INTO @X (ID) VALUES (2)

INSERT INTO @A (ID, FKID, Value, Sort) VALUES (1, 1, 'a',     1)
INSERT INTO @A (ID, FKID, Value, Sort) VALUES (2, 1, 'aa',    2)
INSERT INTO @A (ID, FKID, Value, Sort) VALUES (3, 1, 'aaa',   3)
INSERT INTO @A (ID, FKID, Value, Sort) VALUES (4, 2, 'aaaa',  1)
INSERT INTO @A (ID, FKID, Value, Sort) VALUES (5, 2, 'aaaaa', 2)

INSERT INTO @B (ID, FKID, Value, Sort) VALUES (1, 1, 'b',     1)
INSERT INTO @B (ID, FKID, Value, Sort) VALUES (2, 1, 'bb',    2)
INSERT INTO @B (ID, FKID, Value, Sort) VALUES (3, 2, 'bbb',   1)
INSERT INTO @B (ID, FKID, Value, Sort) VALUES (4, 2, 'bbbb',  2)
INSERT INTO @B (ID, FKID, Value, Sort) VALUES (5, 2, 'bbbbb', 3)

SELECT * FROM @X
SELECT * FROM @A
SELECT * FROM @B

SELECT COALESCE(A.FKID, B.FKID) ID
  ,A.Value
  ,B.Value
  ,COALESCE(A.Sort, B.Sort) Sort
FROM @X X
LEFT JOIN @A A ON A.FKID = X.ID
FULL OUTER JOIN @B B ON B.FKID = A.FKID AND B.Sort = A.Sort

Answer 1

select 
    coalesce(a.fkid, b.fkid) fkid, 
    A.Value as ValueA, 
    B.Value as ValueB, 
    coalesce(a.sort, b.sort) Sort
from a full outer join b
        on a.fkid = b.fkid
        and a.sort = b.sort
order by fkid, sort

Answer 2

我不是100％清楚你所追求的是什么，但试试这个，看看它是不是你想要的

Select Coalesce(a.FKID, b.FKID) FKID,
    a.Value, B.Value, 
    Coalesce(a.Sort, b.Sort) Sort
From TableA a Full Join TableB b
    On a.Sort = b.sort
       And Left(a.value,1) = 'a'
       And Left(b.value,1) = 'b'
       And Len(a.value) = Len(b.value)

Answer 3

SELECT A.FKID,  A.Value AS ValueA, B.Value AS ValueB, A.Sort
FROM Table1 AS A LEFT JOIN Table2 AS B
ON A.ID = B.ID AND A.FKID = B.FKID
UNION 
SELECT B.FKID,  A.Value AS ValueA, B.Value AS ValueB, B.Sort
FROM Table1 AS A RIGHT JOIN Table2 AS B
ON A.ID = B.ID AND A.FKID = B.FKID

注意：这将返回重复记录以匹配ID＆amp; FKID（排序不同）。如果从查询中删除“排序”字段，您将获得正在查找的结果。

SELECT A.FKID,  A.Value AS ValueA, B.Value AS ValueB, A.Sort AS ASort, 
B.Sort AS BSort
FROM Table1 AS A LEFT JOIN Table2 AS B
ON A.ID = B.ID AND A.FKID = B.FKID
UNION 
SELECT B.FKID,  A.Value AS ValueA, B.Value AS ValueB,
A.Sort AS ASort, B.Sort AS BSort
FROM Table1 AS A RIGHT JOIN Table2 AS B
ON A.ID = B.ID AND A.FKID = B.FKID

Answer 4

select COALESCE(tt1.FKID, tt2.FKID) FKID, 
       tt1.Value ValueA, 
       tt2.Value ValueB,
       CASE WHEN tt1.Sort IS NULL OR tt2.Sort IS NULL
            THEN COALESCE(tt1.Sort, tt2.Sort)
            ELSE CASE WHEN tt1.Sort >= tt2.Sort 
                      THEN tt1.Sort 
                      ELSE tt2.Sort
                 END
       END Sort 
from tt1
full join tt2 on tt1.FKID = tt2.FKID and len(tt1.value) = len(tt2.value)
order by COALESCE(tt1.FKID, tt2.FKID)

SQLServer：如何为任意（和不等长）的序列配对有序数据？

4 个答案: