Question

我有一张表格，格式如下： -

 Column A  Column B      Column C
   a          b             NULL
                            06/13/2012
                            08/11/2012
   C           D            NULL
                            09/11/2011
   E          F             NULL
                            06/13/2012
                            09/11/2012

需要输出的地方

Column A  Column B      Column C
       a          b       06/13/2012
       a          b       08/11/2012                                     
       C          D       09/11/2011   
       E          F       06/13/2012   
       E          F       09/11/2012

有没有办法可以循环更新A列和B列。即以不同的A列和B列的组合开始，并更新该列的剩余行，直到我们达到新的不同值。比较更新列A和列B与a和b，直到新值（C，D）

Answer 1

INSERT INTO TableStack VALUES 
 (  'a',         'b',NULL)
,( '' ,'','06/13/2012')
,( '' ,'','08/11/2012')
,('C',           'D',NULL)
,( '' ,'','09/11/2011')
,('E',          'F',NULL)
,( '' ,'','06/13/2012')
,( '' ,'','09/11/2012')

--delete from TableStack


SELECT [Column A]
      ,[Column B]
      ,[Column C]
INTO #STACK 
FROM TableStack

ALTER TABLE #STACK
ADD ModifiedA varchar(10),
ModifiedB varchar(10)

declare @t varchar(10)=''
update t
set ModifiedA=@t,
@t=@t+[column A]
from #STACK t

declare @t varchar(10)=''
update t
set ModifiedB=@t,
@t=@t+[column B]
from #STACK t

SELECT *,case when len(ModifiedA)=2 then right(ModifiedA,1)
when len(ModifiedA)=3 then  right(ModifiedA,1) else ModifiedA end A,
case when len(ModifiedB)=2 then right(ModifiedB,1)
when len(ModifiedB)=3 then  right(ModifiedB,1) else ModifiedB end B
 INTO #StackNew
 FROM #STACK

 update s
 set s.[column a]=s.A,
 s.[Column B]=s.B
 from #StackNew s

 SELECT [column a],[Column B],[Column C] FROM #StackNew
 WHERE [Column C] is not null

Answer 2

如果您的第一个表中有主键或任何唯一的行，那么您可以将其存储在临时表中并开始循环直到新值出现

您可以参考下面的查询来了解如何操作

Select   ROW_NUMBER() OVER (ORDER BY ColumnC ) AS RowNumber,ColumnA,  ColumnB, ColumnC   --you are getting top table as asked in question
Into   #Temp
From   TableName

Declare @ColumnA VARCHAR(1) 
Declare @ColumnB VARCHAR(1) 
DECLARE @RowNumber INT

Declare @LastColumnA VARCHAR(1) 
Declare @LastColumnA VARCHAR(1) 


While (Select Count(*) From #Temp) > 0
Begin

    Select Top 1 @RowNumber = RowNumber, @ColumnA = ColumnA, @ColumnB=ColumnB  From #Temp  ORDER BY ColumnC

    IF ISNULL(@ColumnA,'') = ''
    BEGIN
      --update previous columns because its blank
      UPDATE TableName SET ColumnA= @LastColumnA, ColumnB = @LastColumnB WHERE -- if primary key is there use it else use all where condition below
      ColumnA = @ColumnA and ColumnB=@ColumnB and  ColumnC=@ColumnC
    END
    ELSE
    BEGIN
        SET @LastColumnA = @ColumnA;
     --Get New  columns because its blank
    END
    --Do some processing here

    Delete FROM #Temp Where RowNumber = @RowNumber

End

此查询未经过测试，您可以将其引用为逻辑

在Loop中更新Sql列

2 个答案: