有沒有辦法將選擇查詢的結果拆分爲兩個相等的半部分？

Question

我需要在Sql Server 2005中的選擇查詢的解決方案。

我想有一個查詢返回兩個ResultSets，其中每個都持有一半匹配特定條件的所有記錄。我嘗試將TOP 50 PERCENT與Order By結合使用，但如果表中的記錄數是奇數，則兩個結果集中都會顯示一條記錄。我不想在記錄集上有任何重複的記錄。例如：

我有一個簡單的表，TheID（PK）和TheValue字段（varchar（10））和5條記錄。現在跳過where子句。

SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID asc 

結果在所選擇的ID 1,2,3

SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID desc 

結果在所選擇的ID 3,4,5-

3是DUP。在現實生活中，當然查詢對於大量的where子句和子查詢來說相當複雜。

Answer 1

SQL Server 2005和類似：

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

ntile(n)分配輸出到N段，每個相同的大小（或採取時四捨五入行數不能被n整除）。因此，這將產生輸出：

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

如果你只是想在頂部或底部的一半，你需要把這個變成一個子查詢，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 

將返回的上半部分，同樣使用x.tile_nr = 2的下半部

Answer 2

你可以使用這兩個查詢：

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

試試這個：

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 4

如果這是SQL Server 2000中，那麼我會傾向於尋找中間值的PK，像這樣：

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 

在SQL Server 2005，我會傾向於做同樣的，但你可以使用一個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 5

這是the query我發現有用（的道的修改後）：

DECLARE @numberofitemsperpage INT DECLARE @numberofpages INT DECLARE @currentpage詮釋

DECLARE @countRecords浮動SET @countRecords =（SELECT COUNT（*）FROM sz_hold_visitsData） - 在Excel中可以同時容納約一百萬條記錄。如果@countRecords> = 1000000 SET @numberofitemsperpage = 500000 ELSE IF @countRecords < 1000000及@countRecords> = 500000 SET @numberofitemsperpage = 250000 ELSE IF @countRecords < 500000 AND @countRecords> = 100000 SET @numberofitemsperpage = 50000 ELSE SET @numberofitemsperpage = 10000

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

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

SET @currentpage = 0 WHILE @currentpage < @numberofpages BEGIN SELECT 一個。* FROM（SELECT ROW_NUMBER）OVER（ORDER（BY PERSON_ID）AS ROW，* FROM sz_hold_visitsData）一個WHERE ROW> = @currentpage * @numberofitemsperpage 1和行< =（@當前第+ 1）* @numberofitemsperpage

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

在此摘錄中，「sz_hold_visitsData」是我的數據庫中的一個表，而「person_ID」是其中的一列。 您還可以進一步修改腳本以輸出到文件：

DECLARE @numberofitemsperpage INT DECLARE @numberofpages INT DECLARE @currentpage詮釋

DECLARE @countRecords浮SET @countRecords =（SELECT COUNT（*）從 sz_hold_visitsData） - Excel一次可以保存大約一百萬條記錄。如果@countRecords> = 1000000 SET @numberofitemsperpage = 500000 ELSE IF @countRecords < 1000000及@countRecords> = 500000 SET @numberofitemsperpage = 250000 ELSE IF @countRecords < 500000 AND @countRecords> = 100000 SET @numberofitemsperpage = 50000 ELSE SET @numberofitemsperpage = 10000

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

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

DECLARE @sevrName爲nvarchar（50）SET @sevrName =」 \ sql14' DECLARE @outputfile爲nvarchar（500）

SET @currentpage = 0 WHILE @currentpage < @numberofpages BEGIN - 選擇一個* FROM（SELECT row_number（）OVER（ORDER BY person_ID）AS ROW，* FROM sz_hold_visitsData）WHERE ROW> = @currentpage * @numberofitemsperpage +1 AND行< = （@ currentpage + 1）* @numberofitemsperpage SET @outputFile ='C：\ PSM \ outVisits_' + convert（nvarchar（50），@currentpage）+'。csv' - 選擇@outputFile --TEST

DECLARE @cmd_ varchar（500）='sqlcmd -S'+ @sevrName +'-E -Q 「SELECT a。* FROM（SELECT row_number（）OVER ORDER BY PERSON_ID）AS ROW，* FROM sz_hold_visitsData）一個WHERE ROW> = '+ CONVERT（nvarchar的（500），@當前頁* @numberofitemsperpage 1）+' AND 行< ='+ CONVERT（nvarchar的（500） ，（（@ currentpage + 1）* @numberofitemsperpage））+'「-s」，「-o'+ @ outputFile +'' - 」C：\ PSM \ outVisits.csv「'EXEC xp_cmdshell @cmd_

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

希望有所幫助。

Answer 6

這裏是另一種解決方案：

你需要使用一個臨時表來保存如下第一50％：

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)