转自：http://msdn.microsoft.com/en-us/library/ms186734.aspx

ROW_NUMBER (Transact-SQL)

SQL Server 2008 R2 Other Versions    SQL Server "Denali" SQL Server 2008 SQL Server 2005

Returns the sequential number of a row within a partition of a result set, starting at 1 for the first row in each partition.

Transact-SQL Syntax Conventions

Syntax

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Copy ROW_NUMBER ()     OVER ( [ <partition_by_clause> ] <order_by_clause> ) Arguments

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< partition_by_clause>

Divides the result set produced by the FROM clause into partitions to which the ROW_NUMBER function is applied. For the PARTITION BY syntax, see OVER Clause (Transact-SQL).

< order_by_clause>

Determines the order in which the ROW_NUMBER value is assigned to the rows in a partition. For more information, see ORDER BY Clause (Transact-SQL). An integer cannot represent a column when the <order_by_clause> is used in a ranking function.

Return Types

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bigint

Remarks

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The ORDER BY clause determines the sequence in which the rows are assigned their unique ROW_NUMBER within a specified partition.

Examples

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A. Returning the row number for salespeople

The following example returns the ROW_NUMBER for the salespeople in AdventureWorks2008R2 based on the year-to-date sales.

Copy SELECT FirstName, LastName, ROW_NUMBER() OVER(ORDER BY SalesYTD DESC) AS 'Row Number', SalesYTD, PostalCode FROM Sales.vSalesPerson WHERE TerritoryName IS NOT NULL AND SalesYTD <> 0;

B. Returning a subset of rows

The following example returns rows with numbers 50 to 60 inclusive in the order of the OrderDate.

Copy USE AdventureWorks2008R2; GO WITH OrderedOrders AS ( SELECT SalesOrderID, OrderDate, ROW_NUMBER() OVER (ORDER BY OrderDate) AS 'RowNumber' FROM Sales.SalesOrderHeader ) SELECT * FROM OrderedOrders WHERE RowNumber BETWEEN 50 AND 60;

C. Using ROW_NUMBER() with PARTITION

The following example shows using the ROW_NUMBER function with the PARTITION BY argument.

Copy SELECT FirstName, LastName, ROW_NUMBER() OVER(PARTITION BY PostalCode ORDER BY SalesYTD DESC) AS 'Row Number', SalesYTD, PostalCode FROM Sales.vSalesPerson WHERE TerritoryName IS NOT NULL AND SalesYTD <> 0; See Also

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Reference

RANK (Transact-SQL) DENSE_RANK (Transact-SQL) NTILE (Transact-SQL) Ranking Functions (Transact-SQL) Built-in Functions (Transact-SQL)

转载于:https://www.cnblogs.com/fightLonely/archive/2011/02/24/1963889.html