将上一行值复制到sql中的所有下一行

Question

我需要将以前的行值复制到sql server中的下一行。

使用LAG功能，我只能为下一行实现这一功能。但我必须复制多行。

以下是示例示例：

Answer 1

查询：

SELECT
    t1.ID,
    t1.CustID,
    t2.ID,
    t2.CustID,
    t2.Flag,
    COALESCE(
        t2.Flag,
        (
            SELECT TOP 1 l.Flag 
            FROM TBL2 l
            WHERE l.CustID = t1.CustID AND l.ID < t1.ID
            ORDER BY l.ID desc
        )) as 'Final'
FROM
    TBL1 t1
    LEFT OUTER JOIN TBL2 t2 ON t2.ID = t1.ID AND t2.CustID = t1.CustID
ORDER BY
    t1.CustID,
    t1.ID desc

设定：

CREATE TABLE TBL1 (ID int, CustID int)
GO

CREATE TABLE TBL2 (ID int, CustID int, Flag bit)
GO

INSERT INTO TBL1 (ID, CustID)
SELECT 1, 11 UNION ALL
SELECT 1, 12 UNION ALL
SELECT 1, 13 UNION ALL
SELECT 1, 14 UNION ALL
SELECT 1, 15 UNION ALL
SELECT 1, 16 UNION ALL
SELECT 1, 17 UNION ALL
SELECT 2, 11 UNION ALL
SELECT 2, 12 UNION ALL
SELECT 2, 13 UNION ALL
SELECT 2, 14 UNION ALL
SELECT 2, 15 UNION ALL
SELECT 2, 16 UNION ALL
SELECT 2, 17 UNION ALL
SELECT 3, 11 UNION ALL
SELECT 3, 12 UNION ALL
SELECT 3, 13 UNION ALL
SELECT 3, 14 UNION ALL
SELECT 3, 15 UNION ALL
SELECT 3, 16 UNION ALL
SELECT 3, 17 UNION ALL
SELECT 4, 11 UNION ALL
SELECT 4, 12 UNION ALL
SELECT 4, 13 UNION ALL
SELECT 4, 14 UNION ALL
SELECT 4, 15 UNION ALL
SELECT 4, 16 UNION ALL
SELECT 4, 17

GO

INSERT INTO TBL2 (ID, CustID, Flag)
SELECT 1, 11, 0 UNION ALL
SELECT 1, 12, 1 UNION ALL
SELECT 1, 13, 1 UNION ALL
SELECT 1, 14, 0 UNION ALL
SELECT 1, 15, 0 UNION ALL
SELECT 1, 16, 0 UNION ALL
SELECT 1, 17, 1 UNION ALL
SELECT 2, 11, 1 UNION ALL
SELECT 2, 13, 0 UNION ALL
SELECT 2, 14, 1 UNION ALL
SELECT 2, 15, 1 UNION ALL
SELECT 2, 17, 0 UNION ALL
SELECT 3, 13, 1 UNION ALL
SELECT 3, 15, 0 UNION ALL
SELECT 3, 17, 1 UNION ALL
SELECT 4, 12, 0 UNION ALL
SELECT 4, 17, 0

GO

Answer 2

你可以试试这个：

SELECT *
      ,ISNULL(b.flag,(MAX(b.flag) OVER (PARTITION BY a.[custid] ORDER BY b.[id] DESC ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)))
FROM @TBL1 A
LEFT JOIN @TBL2 B
    ON A.id = b.id
    AND A.custid = b.custid
ORDER BY a.[custid] ASC, a.[id] DESC

以下是示例数据：

DECLARE @TBL1 TABLE
(
    [id] TINYINT
   ,[custid] TINYINT
);

DECLARE @TBL2 TABLE
(
    [id] TINYINT
   ,[custid] TINYINT
   ,[flag] TINYINT
);

INSERT INTO @TBL1([id], [custid])
VALUES 
(1,11)
,(1,12)
,(1,13)
,(1,14)
,(1,15)
,(1,16)
,(1,17)
,(2,11)
,(2,12)
,(2,13)
,(2,14)
,(2,15)
,(2,16)
,(2,17)
,(3,11)
,(3,12)
,(3,13)
,(3,14)
,(3,15)
,(3,16)
,(3,17)
,(4,11)
,(4,12)
,(4,13)
,(4,14)
,(4,15)
,(4,16)
,(4,17);

INSERT INTO @TBL2 ([id], [custid], [flag])
VALUES (1,11,0)
,(1,12,1)
,(1,13,1)
,(1,14,0)
,(1,15,0)
,(1,16,0)
,(1,17,1)
,(2,11,1)
,(2,13,0)
,(2,14,1)
,(2,15,1)
,(2,17,0)
,(3,13,1)
,(3,15,0)
,(3,17,1)
,(4,12,0)
,(4,17,0)

Answer 3

您可以使用LEFT JOIN，CASE EXPRESSION和相关查询：

SELECT t.id,t.custid,s.id,s.custid,
       COALESCE(s.flag,(SELECT TOP 1 ss.flag FROM tbl2 ss
                        WHERE ss.custid = t.custid and ss.id < t.id
                        ORDER BY ss.id DESC)) as flag
FROM Tbl1 t
LEFT JOIN tbl2 s
 ON(t.custid = s.custid and s.id = t.id)