Fetch Data Using While Loop From A Table With Identity Column

A simple way to fetch data one by one using while loop if table has a identity or primary key.

Assume that I am using the below table and need to fetch one by one all rows and do some operation on each row data. 

 

Table structure 

CREATE TABLE [dbo].[User_Login](
[userid] [int] IDENTITY(1,1) NOT NULL,
[Username] [varchar](100) NULL,
[User_Pass] [varchar](100) NULL,
[F_Name] [varchar](20) NULL,
[L_Name] [varchar](20) NULL,
[Address1] [varchar](200) NULL,
[mobile] [varchar](20) NULL,
[City] [varchar](20) NULL
)

We can use a while loop, get the column data and do some operations.  

declare @cnt int
declare @UnitCount int
set @cnt=1
set @UnitCount=(select count(*) from User_Login)
while @cnt<@UnitCount
begin
select top(1)* from User_Login where userid not in(select top(@cnt-1) userid from User_Login) order by userid
--Do your operation like fetch data into variables and update it into another table etc..
set @cnt=@cnt+1
end