pivot

简单

SELECT DaysToManufacture, AVG(StandardCost) AS AverageCost 
FROM Production.Product
GROUP BY DaysToManufacture;

结果

DaysToManufacture          AverageCost

0                          5.0885

1                          223.88

2                          359.1082

4                          949.4105

复杂

SELECT VendorID, [250] AS Emp1, [251] AS Emp2, [256] AS Emp3, [257] AS Emp4, [260] AS Emp5
FROM 
(SELECT PurchaseOrderID, EmployeeID, VendorID
FROM Purchasing.PurchaseOrderHeader) p
PIVOT
(
COUNT (PurchaseOrderID)
FOR EmployeeID IN
( [250], [251], [256], [257], [260] )
) AS pvt
ORDER BY pvt.VendorID;
结果

VendorID    Emp1        Emp2        Emp3        Emp4        Emp5

1492        2           5           4           4           4

1494        2           5           4           5           4

1496        2           4           4           5           5

1498        2           5           4           4           4

1500        3           4           4           5           4