create table t_dates
(id int not null,
archive datetime,
expiry datetime,
caseif char(1)
)

insert into t_dates (id, archive, expiry, caseif) values (1, getdate(), getdate()+3, 0) 
insert into t_dates (id, archive, expiry, caseif) values (2, getdate(), getdate()-5, 0)
insert into t_dates (id, archive, expiry, caseif) values (3, getdate(), getdate()+12, 0)
insert into t_dates (id, archive, expiry, caseif) values (4, getdate(), getdate()+3, 0)


update t_dates
set caseif = 1
where archive >= expiry

update t_dates

set archive = 
	case when (archive < expiry ) then archive
		when (archive >= expiry) then expiry
		end

update myTable set
	Archived = 1
from	myTable
where	ExpiryDate <= getdate()
and	Archived is NULL