????? PIVOT，UNPIVOT運算符是SQL server 2005支持的新功能之一，主要用來實現行到列的轉換。本文主要介紹PIVOT運算符的操作，以及如何實現動態PIVOT的行列轉換。??????

一、PIVOT的語法

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SELECT [non-pivoted column], -- optional [additional non-pivoted columns], -- optional [first pivoted column], [additional pivoted columns] FROM ( SELECT query producing sql data for pivot -- select pivot columns as dimensions and -- value columns as measures from sql tables ) AS TableAlias PIVOT ( <aggregation function>(column for aggregation or measure column) -- MIN,MAX,SUM,etc FOR [] IN ( [first pivoted column], ..., [last pivoted column] ) ) AS PivotTableAlias ORDER BY clause – optional

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1. 靜態PIVOT的用法
?????? 為演示，從NorthWind數據庫中提取一些記錄生成新的Orders表，然后使用PIVOT將行轉換到列。

USE tempdb GO SELECT YEAR(OrderDate) AS [Year],CustomerID ,od.Quantity INTO dbo.Orders FROM NorthWind..Orders AS oJOIN NorthWind..[Order Details] AS odON o.OrderID = od.OrderID WHERE o.CustomerID IN ('BONAP','BOTTM','ANTON') SELECT CustomerID,[1996],[1997],[1998] FROM dbo.Orders PIVOT (SUM(Quantity)FOR [Year] IN ([1996],[1997],[1998]))x /* TSQL中pivot的結構：● 用于生成pivot數據源的源表，作為一個輸入表● pivot表● 聚合列及透視列的選擇TSQL中pivot的實現： 1->上例中Orders表相當于是一個輸入表。包含了CustomerID,[Year],Quantity 三個列。Year是透視列，用于生成維度。pivot首先將聚合列之外的列進行分組，并對其實現聚合。本列中則是對聚合列Quantity之外的列先實現分組，即對CustomerID，Year進行分組，并對其Quantity實現聚合，相當于先做如下處理： */ SELECT CustomerID,[Year],SUM(Quantity) AS Total FROM dbo.Orders GROUP BY CustomerID,[Year] ORDER BY CustomerID /* Result: CustomerID Year Total ---------- ----------- ----------- ANTON 1996 24 ANTON 1997 295 ANTON 1998 40 BONAP 1996 181 BONAP 1997 486 BONAP 1998 313 BOTTM 1996 81 BOTTM 1997 454 BOTTM 1998 421 */ /* 2->pivot根據FOR [Year] IN子句中的值，在結果集中來建立對應的新列，本例中即是列，，對于新列，，中的取值，取中間結果集中與之相對應的值。如對于客戶ANTON，1996列中的值就選擇中間結果中對應的Total值，同理列中為。并將中間結果pivot表命名為x。3->最外層的SELECT語句從pivot表生成最終結果,此處因Orders表僅有列，故直接將結果用一個SELECT返回，有嵌套的SELECT參照下例。--結果: CustomerID 1996 1997 1998 ---------- ----------- ----------- ----------- ANTON 24 295 40 BONAP 181 486 313 BOTTM 81 454 421 */ 以下是為輸入表多于一列的例子,數據來源于SQL server 2005的AdventureWorks，其實現的原理同上。 SELECT * FROM(SELECT YEAR(DueDate) [Year],CASE MONTH(DueDate)WHEN 1 THEN 'January' WHEN 2 THEN 'February'WHEN 3 THEN 'March'WHEN 4 THEN 'April'WHEN 5 THEN 'May'WHEN 6 THEN 'June'WHEN 7 THEN 'July'WHEN 8 THEN 'August'WHEN 9 THEN 'September'WHEN 10 THEN 'October'WHEN 11 THEN 'November'WHEN 12 THEN 'December'END as [Month],ProductID,OrderQtyFROM Production.WorkOrder )WorkOrderPIVOT (SUM(OrderQty)FOR [Month] IN ([January],[February],[March],[April],[May],[June],[July],[August],[September],[October],[November],[December]))x ORDER BY [Year], ProductID --Result: 末尾部分省略 /* Year ProductID January February March April May June July August ----------- ----------- ----------- ----------- ----------- ----------- ----------- ----------- ----------- ----------- 2002 3 8480 16870 12960 9530 19390 14170 26200 35870 2002 316 1842 3704 2910 2252 4738 3496 7624 10778 2002 324 1842 3704 2910 2252 4738 3496 7546 10600 2002 327 921 1852 1455 1126 2369 1748 3773 5300 2002 328 414 1048 872 458 1272 992 1786 2632 */

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2. 動態PIVOT的使用

USE AdventureWorks; GO --第一種生成透視列的方法，使用了COALESCE來聯接字符串 DECLARE @PivotColHeader VARCHAR(MAX) SELECT @PivotColHeader =COALESCE(@PivotColHeader + ',[' + cast(Name as varchar) + ']','[' + cast(Name as varchar) + ']') --示例中Name轉換為varchar或char類型，注意：在CAST 和CONVERT 中使用varchar 時，顯示n的默認值為30 FROM Sales.SalesTerritory GROUP BY Name/* --第二種生成透視列的方法，使用了FOR XML PATH方法 SELECT @PivotColHeader = STUFF(( SELECT DISTINCT ',[' + cast(Name as varchar) + ']'FROM Sales.SalesTerritoryFOR XML PATH('')),1,1,'') */DECLARE @PivotTableSQL NVARCHAR(MAX) SET @PivotTableSQL = N'SELECT *FROM (SELECT YEAR(H.OrderDate) [Year],T.Name,H.TotalDueFROM Sales.SalesOrderHeader HLEFT JOIN Sales.SalesTerritory TON H.TerritoryID = T.TerritoryID)AS PivotDataPIVOT(SUM(TotalDue)FOR Name IN (' + @PivotColHeader + ')) AS x ' EXECUTE sp_executesql @PivotTableSQL --Result:部分結果省略 /* Year Australia Canada Central France Germany Northeast ----------- --------------------- --------------------- --------------------- --------------------- --------------------- --------------------- 2001 1446497.1744 2173647.1453 1263884.1024 199531.723 262752.4184 754833.2045 2002 2380484.8387 7215430.5017 3518185.4756 1717145.7439 575960.0974 3275322.1694 2003 4547123.2777 8186021.9178 4015356.874 4366078.3475 2714826.4297 3833030.25 2004 3823410.2386 3926712.8926 1771532.7396 2853948.6596 2386224.5508 1406555.6861 */

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?? 對該動態pivot增加匯總列

DECLARE @PivotColHeader VARCHAR(MAX) DECLARE @TotalCol VARCHAR(MAX)SELECT @PivotColHeader = --使用COALESCE函數生成列標題COALESCE(@PivotColHeader + ',[' + cast(Name as varchar) + ']','[' + cast(Name as varchar) + ']'),@TotalCol = COALESCE(@TotalCol + ', SUM([' + cast(Name as varchar) + ']) AS [' + cast(Name as varchar) + ']','SUM([' + cast(Name as varchar) + ']) AS [' + cast(Name as varchar) + ']') --使用COALESCE函數生成匯總字符串 FROM Sales.SalesTerritoryDECLARE @PivotTableSQL NVARCHAR(MAX) SET @PivotTableSQL = N'SELECT *FROM (SELECT CAST(YEAR(H.OrderDate) AS CHAR(4)) [Year],T.Name,H.TotalDueFROM Sales.SalesOrderHeader HLEFT JOIN Sales.SalesTerritory TON H.TerritoryID = T.TerritoryID)AS PivotDataPIVOT(SUM(TotalDue)FOR Name IN (' + @PivotColHeader + ')) AS x UNION SELECT ''GrandTotal'', ' + @TotalCol + 'FROM (SELECT CAST(YEAR(H.OrderDate) AS CHAR(4)) [Year],T.Name,H.TotalDueFROM Sales.SalesOrderHeader HLEFT JOIN Sales.SalesTerritory TON H.TerritoryID = T.TerritoryID) AS PivotData PIVOT(SUM(TotalDue)FOR Name IN (' + @PivotColHeader + ')) AS y ' --PRINT @PivotTableSQL EXECUTE sp_executesql @PivotTableSQL --Result:部分結果省略 /* Year Australia Canada Central France Germany Northeast Northwest ---------- --------------------- --------------------- --------------------- --------------------- --------------------- --------------------- --------------------- 2001 1446497.1744 2173647.1453 1263884.1024 199531.723 262752.4184 754833.2045 2703481.7947 2002 2380484.8387 7215430.5017 3518185.4756 1717145.7439 575960.0974 3275322.1694 5651688.6685 2003 4547123.2777 8186021.9178 4015356.874 4366078.3475 2714826.4297 3833030.25 7494658.0357 2004 3823410.2386 3926712.8926 1771532.7396 2853948.6596 2386224.5508 1406555.6861 4952772.2793 GrandTotal 12197515.5294 21501812.4574 10568959.1916 9136704.474 5939763.4963 9269741.31 20802600.7782 */

生成匯總列的注意事項;
??? 1->使用COALESCE函數生成列標題 。
??? 2->使用COALESCE函數生成帶有SUM求和函數并且指定了別名的字符串。
??? 3->使用UNION對兩個SELECT來實現聯接。且將[Year]轉換為字符串，因為YEAR(H.OrderDate)得值為 INT ，而''GrandTotal''為字符串，UNION 或UNION ALL使用時必須列的數量和類型相對應。

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引用地址：http://blog.csdn.net/robinson_0612/article/details/5385117

轉載于:https://www.cnblogs.com/hongyuniu/archive/2013/05/07/3064911.html

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