How to generate ROWNUM in SQL Server SELECT

It is often required to create unique values for every row in a result set query in SQL Server. But SQL Server doesn’t have any built in functions such as ROWNUM in oracle to support this feature. There are many ways in which we can generate unique numbers in the select query as shown in the below scenario

Consider the Employee table with EmployeeName and EmployeeID columns and the scenario is to select records from the table based on EmployeeID with uniqueid for each row in the result set. The select statement can be written in below ways

Create table Employee ( EmployeeID INT , EmployeeName Varchar(30))
ROWNUM using ROW_NUMBER
SELECT ROW_NUMBER () OVER (ORDER BY EmployeeID) AS RowNumber, EmployeeName
FROM Employee ORDER BY EmployeeID
ROWNUM using IDENTITY
SELECT IDENTITY(int, 100, 1) AS RowNumber , EmployeeName
INTO #tmp
FROM Employee ORDER BY EmployeeID
SELET RowNumber , EmployeeID FROM #tmp
ROWNUM using NEWID
SELECT NEWID() ,AS RowNumber, EmployeeName FROM Employee
ORDER BY EmployeeID
Related article:
http://samsudeenb.blogspot.com/2009/06/how-to-generate-sequence-number-in-sql.html

Paging with MS SQL Server 2005

Paging can be easily achieved in MS SQL Server 2005 by using the ROW_NUMBER function and CTE (Common Table Expressions). The ROW_NUMBER function provides the ability to issue a query and just return a subset of the result set and the CTE allows us to define the temporary result set with clause. The below example shows how to retrieve first ten Patients from a result set using the CTE and ROW_NUMBER function.

USE Patient_DB;
GO
WITH PatientDetail
AS
(
SELECT
Surname,
Forename,
Age,
ROW_NUMBER() OVER (order by Surname) AS 'RowNumber'
FROM Patient
)
SELECT * FROM
PatientDetail
WHERE
RowNumber between 1 and 10;
GO

The OVER clause is used to determine the partitioning and ordering of the intermediary result set before the ROW_NUMBER function is applied. The SELECT statement can be parameterized to retrieve data for the specified Range as given below.

USE Patient_DB;
GO
WITH PatientDetail
AS
(
SELECT
Surname,
Forename,
Age,
ROW_NUMBER() OVER (order by Surname) AS 'RowNumber'
FROM Patient
)

SELECT * FROM
PatientDetail
WHERE RowNumber between
@RowNumberFrom and @RowNumberTo;
GO