Question

我需要在Sql Server 2005中为select查询提供解决方案。

我想让一个查询返回两个ResultSet，每个ResultSet都保留了与某个条件匹配的所有记录的一半。我尝试将TOP 50 PERCENT与Order By结合使用但是如果表中的记录数是奇数，则两个结果集中都会显示一条记录。我不想在记录集上复制任何记录。例如：

我有一个带有TheID（PK）和TheValue字段（varchar（10））的简单表和5条记录。暂时跳过where子句。

SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID asc

导致所选id为1,2,3

SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID desc

导致所选ID为3,4,5

3是一个副本。在现实生活中，查询相当复杂，有大量where子句和子查询。

Answer 1

SQL Server 2005及类似程序：

select *, ntile(2) over(order by theid) as tile_nr from thetable

ntile(n)将输出分配到n个段中，每个段具有相同的大小（当行数不能被n整除时给予或舍入）。所以这会产生输出：

1 | value1 | 1
2 | value2 | 1
3 | value3 | 1
4 | value4 | 2
5 | value5 | 2

如果您只想要上半部分或下半部分，则需要将其放入子查询中，例如：

select theid, thevalue from (
  select theid, thevalue, ntile(2) over(order by theid) as tile_nr from thetable
) x
where x.tile_nr = 1

将返回上半部分，同样使用x.tile_nr = 2作为下半部分

Answer 2

您可以使用以下两个查询：

SELECT * FROM (
    SELECT *, ROW_NUMBER() OVER (ORDER BY TheID) AS rn FROM TheTable
) T1
WHERE rn % 2 = 0

SELECT * FROM (
    SELECT *, ROW_NUMBER() OVER (ORDER BY TheID) AS rn FROM TheTable
) T1
WHERE rn % 2 = 1

Answer 3

如果这是SQL Server 2000，那么我倾向于找到中间值的PK，如下所示：

Declare @MiddleId int

Set @MiddleId = (
                Select TOP 1 PK
                From (
                        Select TOP 50 PERCENT PK
                        From Table
                        Order By TheId ASC
                        )
                Order By TheId DESC
                )

Select ...
From Table
Where TheId <= @MiddleId

Select ..
From Table
Where TheId > @MiddleId

使用SQL Server 2005，我倾向于这样做但你可以使用CTE

;With NumProjects As
    (
    Select Id, ROW_NUMBER() OVER (ORDER BY TheId ASC ) As Num
    From Table
    )
Select @MiddleId = Id
From Table
Where Num = CEILING( (Select Count(*) From Table) / 2 )

Answer 4

试试这个：

DECLARE @CountOf int,@Top int,@Bottom int
SELECT @CountOf=COUNT(*) FROM YourTable
SET @Top=@CountOf/2
SET @Bottom=@CountOf-@Top
SELECT TOP (@Top) * FROM YourTable ORDER BY 1 asc --assumes column 1 is your PK
SELECT TOP (@Bottom) * FROM YourTable ORDER BY 1 desc --assumes column 1 is your PK

Answer 5

这是另一种解决方案：

您需要使用临时表来保存前50％，如下所示：

select top 50 percent * 
into #YourTempTable
from TheTable 

-- The below would give the first half
select * from #YourTempTable

-- The below woud give rest of the half 
select * from TheTable where TheID not in (select TheID from #YourTempTable)

Answer 6

这是the query我发现有用（经过修改后）：

DECLARE @numberofitemsperpage INT DECLARE @numberofpages INT DECLARE @currentpage int


DECLARE @countRecords float SET @countRecords =（选择COUNT（*）From   sz_hold_visitsData）    - Excel一次可以容纳大约一百万条记录。 if @countRecords＆gt; = 1000000 SET @numberofitemsperpage = 500000 ELSE IF   @countRecords＆lt; 1000000 AND @countRecords＆gt; = 500000 SET   @numberofitemsperpage = 250000 ELSE IF @countRecords＆lt; 500000 AND   @countRecords＆gt; = 100000 SET @numberofitemsperpage = 50000 ELSE SET   @numberofitemsperpage = 10000

DECLARE @numberofpages_deci float SET @numberofpages_deci =   @countRecords / @numberofitemsperpage

SET @numberofpages = CEILING（@numberofpages_deci）选择   @countRecords AS countRecords，@ numberofitemsperpage AS   numberofitemsperpage，@ numberofpages_deci AS numberofpages_deci，   @numberofpages AS numberofpagesFnl

SET @currentpage = 0 WHILE @currentpage＆lt; @numberofpages BEGIN SELECT   a。* FROM（SELECT row_number（）OVER（ORDER BY person_ID）AS ROW，*   FROM sz_hold_visitsData）一个WHERE ROW＆gt; = @currentpage *   @numberofitemsperpage +1 AND Row＆lt; =（@ currentpage + 1）*   @numberofitemsperpage

IF @@ ROWCOUNT = 0 BREAK SET @currentpage = @currentpage +1 END

在此摘录中，＆＃34; sz_hold_visitsData＆＃34;是我数据库中的一个表，而＃34; person_ID＆＃34;是一个专栏。您还可以进一步修改脚本以输出到文件：

DECLARE @numberofitemsperpage INT DECLARE @numberofpages INT DECLARE   @currentpage int

DECLARE @countRecords float SET @countRecords =（选择COUNT（*）From   sz_hold_visitsData）    - Excel一次可以容纳大约一百万条记录。 if @countRecords＆gt; = 1000000 SET @numberofitemsperpage = 500000 ELSE IF   @countRecords＆lt; 1000000 AND @countRecords＆gt; = 500000 SET   @numberofitemsperpage = 250000 ELSE IF @countRecords＆lt; 500000 AND   @countRecords＆gt; = 100000 SET @numberofitemsperpage = 50000 ELSE SET   @numberofitemsperpage = 10000

DECLARE @numberofpages_deci float SET @numberofpages_deci =   @countRecords / @numberofitemsperpage

SET @numberofpages = CEILING（@numberofpages_deci）选择   @countRecords AS countRecords，@ numberofitemsperpage AS   numberofitemsperpage，@ numberofpages_deci AS numberofpages_deci，   @numberofpages AS numberofpagesFnl

DECLARE @sevrName nvarchar（50）SET @sevrName =＆＃39;。\ sql14＆＃39;宣布   @outputFile nvarchar（500）

SET @currentpage = 0 WHILE @currentpage＆lt; @numberofpages BEGIN   --SELECT a。* FROM（SELECT row_number（）OVER（ORDER BY person_ID）AS ROW，* FROM sz_hold_visitsData）WHERE ROW＆gt; = @currentpage *   @numberofitemsperpage +1 AND Row＆lt; =（@ currentpage + 1）*   @numberofitemsperpage SET @outputFile =＆＃39; C：\ PSM \ outVisits _＆＃39;   + convert（nvarchar（50），@ currentpage）+＆＃39; .csv＆＃39; - 选择@outputFile --TEST

DECLARE @cmd_ varchar（500）=＆＃39; sqlcmd -S＆＃39; + @sevrName +＆＃39; -E -Q   ＆＃34; SELECT a。* FROM（SELECT row_number（）OVER（ORDER BY person_ID）AS   ROW，* from sz_hold_visitsData）a WHERE ROW＆gt; =＆＃39; +   CONVERT（nvarchar（500），@ currentpage * @numberofitemsperpage +1）+＆＃39;和   行＆lt; =＆＃39; + CONVERT（nvarchar（500），（（@ currentpage + 1）*   @numberofitemsperpage））+＆＃39;＆＃34; -s＆＃34;，＆＃34; -o＆＃39; + @ outputFile +＆＃39; ＆＃39; -   ＆＃34; C：\ PSM \ outVisits.csv＆＃34; ＆＃39; EXEC xp_cmdshell @cmd _

IF @@ ROWCOUNT = 0 BREAK SET @currentpage = @currentpage +1 END

希望有所帮助。

有没有办法将选择查询的结果分成两个相等的一半？

6 个答案: