create table test1(ID int,UserName nvarchar(10))

select * from test1

insert test1 values (1,'11')

insert test1 values (2,'22')

insert test1 values (3,'33')

insert test1 values (4,'44')

insert test1 values (5,'55')

declare @id int

declare @username varchar(20)

select @id=min(ID) from test1

while @id is not null

begin

 select @username= UserName from test1 where

print @username 

 select @id=min(ID) from test1 where ID>@id

end