更新从上一行非空值空列的值(Update null column value from non nu

@@第1版

使用SQL Server 2008，我想级联值下降的列。我有一个组ID（GID）和含有序列排序为组内记录的表。对于目前的列，在这种情况下姓名和薪水 - 我真正的表有50列，如果它们包含空值我需要更新与前面的一行包含非空值列中的值NULL值。

这是值得说明这一点：

GID Seq Name    Salary
1   1   James   NULL
1   2   NULL    100
1   3   NULL    NULL
2   1   NULL    81
2   2   Smith   NULL
2   3   NULL    NULL
3   1   Charles NULL
3   2   NULL    NULL
3   3   Brown   NULL
3   4   NULL    75
4   0   Ron 50
4   1   NULL    20
4   2   NULL    NULL

我的结果应该是：

GID Seq Name    Salary
1   1   James   NULL
1   2   James   100
1   3   James   100
2   1   NULL    81
2   2   Smith   81
2   3   Smith   81
3   1   Charles NULL
3   2   Charles NULL
3   3   Brown   NULL
3   4   Brown   75
4   0   Ron 50
4   1   Ron 20
4   2   Ron 20

我要做到这一点，而无需使用动态SQL，循环或游标。

代码简单的测试案例：

DECLARE @Test TABLE (GID int, Seq int, Name varchar(50), Salary decimal) 

INSERT INTO @Test VALUES (1, 1, 'James', NULL)
INSERT INTO @Test VALUES (1, 2, NULL, 100.40)
INSERT INTO @Test VALUES (1, 3, NULL, NULL)
INSERT INTO @Test VALUES (2, 1, NULL, 80.50)
INSERT INTO @Test VALUES (2, 2, 'Smith', NULL)
INSERT INTO @Test VALUES (2, 3, NULL, NULL)
INSERT INTO @Test VALUES (3, 1, 'Charles', NULL)
INSERT INTO @Test VALUES (3, 2, NULL, NULL)
INSERT INTO @Test VALUES (3, 3, 'Brown', NULL)
INSERT INTO @Test VALUES (3, 4, NULL, 75)
INSERT INTO @Test VALUES (4, 0, 'Ron', 50)
INSERT INTO @Test VALUES (4, 1, NULL, 20)
INSERT INTO @Test VALUES (4, 2, NULL, NULL)

SELECT * FROM @Test

@@ 2版感谢GilM为解决@@第1版。我已经做了一个小除了问题。在SEQ列的起始编号可以是0或1。在解决第一个问题的递归CTE锚是指1，什么如果其为1或0？在最后3行的数据（GID = 4）加入到在这个版本所有上述三个码块。

谢谢！

Answer 1:

这个怎么样？：

;WITH CTE AS (
SELECT GID, SEQ, Name, Salary
FROM @Test t1
WHERE SEQ = (SELECT MIN(SEQ) FROM @Test t2 WHERE t2.GID = t1.GID)
UNION ALL
SELECT t.GID, t.SEQ, COALESCE(t.Name,c.Name), COALESCE(t.Salary,c.Salary)
FROM CTE c
JOIN @Test t ON t.GID = c.GID AND t.SEQ = c.SEQ+1
)
UPDATE t SET 
    Name = c.Name,
    Salary =  c.Salary
FROM @Test t
JOIN CTE c ON c.GID = t.GID AND c.Seq = t.SEQ

Answer 2:

update T set
  Name =   (
           select top(1) T1.Name
           from @Test as T1
           where T1.GID = T.GID and
                 T1.Seq <= T.Seq and
                 T1.Name is not null
           order by T1.Seq desc
           ),
  Salary = (
           select top(1) T1.Salary
           from @Test as T1
           where T1.GID = T.GID and
                 T1.Seq <= T.Seq and
                 T1.Salary is not null
           order by T1.Seq desc
           )
from @Test as T
where T.Name is null or 
      T.Salary is null

随着50列将有大量的输入和大量的相关子查询。

下面是一个使用XML，而不是一个版本。少打字和表现可能会更好。

with C as
(
  select GID,
         (
         select *
         from @Test as T2
         where T1.GID = T2.GID
         order by T2.Seq desc
         for xml path('row'), type
         ) as X
  from @Test as T1
  group by GID
)
update T set
       Name   = C.X.value('(/row[Seq<=sql:column("T.Seq")]/Name)[1]',   'varchar(50)'),
       Salary = C.X.value('(/row[Seq<=sql:column("T.Seq")]/Salary)[1]', 'decimal')
from @Test as T
  inner join C 
    on T.GID = C.GID

SE-日期

文章来源: Update null column value from non null value in previous row