In this article I am going to show how we can update our existing column value with serial number without using loop. Below is my problem.
I have below table in my SQL Server Data Base:

Image 1.
Table script:
CREATE TABLE [dbo].[Employee_Rank](
[EmployeeName] [varchar](50) NULL,
[Rank] [int] NULL
) ON [PRIMARY]
GO
Data in Table:

Image 2.
Now my requirement is below:

Image 3.
So I wrote below SQL Statement:

Image 4.
DECLARE @SRNO INT =0;
UPDATE EMPLOYEE_RANK SET @SRNO = RANK = @SRNO + 1
SELECT * FROM EMPLOYEE_RANK