OVER 子句 (Transact-SQL)

每个排名函数（ROW_NUMBER、DENSE_RANK、RANK、NTILE）都使用 OVER 子句。以下示例显示了将 OVER 子句与 ROW_NUMBER 结合使用。

USE AdventureWorks2008R2;
GO
SELECT p.FirstName, p.LastName
    ,ROW_NUMBER() OVER(ORDER BY SalesYTD DESC) AS 'Row Number'
    ,s.SalesYTD, a.PostalCode
FROM Sales.SalesPerson s 
    INNER JOIN Person.Person p 
        ON s.BusinessEntityID = p.BusinessEntityID
    INNER JOIN Person.Address a 
        ON a.AddressID = p.BusinessEntityID
WHERE TerritoryID IS NOT NULL 
    AND SalesYTD <> 0;
GO

以下示例显示了将 OVER 子句与聚合函数结合使用。在此示例中，使用 OVER 子句比使用子查询的效率高。

USE AdventureWorks2008R2;
GO
SELECT SalesOrderID, ProductID, OrderQty
    ,SUM(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Total'
    ,AVG(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Avg'
    ,COUNT(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Count'
    ,MIN(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Min'
    ,MAX(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Max'
FROM Sales.SalesOrderDetail 
WHERE SalesOrderID IN(43659,43664);
GO

下面是结果集：

以下示例显示在计算所得值中将 OVER 子句与聚合函数结合使用。

USE AdventureWorks2008R2;
GO
SELECT SalesOrderID, ProductID, OrderQty
    ,SUM(OrderQty) OVER(PARTITION BY SalesOrderID) AS 'Total'
    ,CAST(1. * OrderQty / SUM(OrderQty) OVER(PARTITION BY SalesOrderID) 
        *100 AS DECIMAL(5,2))AS 'Percent by ProductID'
FROM Sales.SalesOrderDetail 
WHERE SalesOrderID IN(43659,43664);
GO

下面是结果集：注意，聚合由 SalesOrderID 计算，并会为每个 SalesOrderID 的每一行计算 Percent by ProductID（ProductID 的百分比）。