Teradata sql - retrieve top and bottom 50 percentage of the records

Top 50%
----------
select top 50 percent  *
from table1
order by id asc

Bottom 50%
---------------
select top 50 percent  *
from table1
order by id desc

Update from select

Update table1
from
(
select
t1.x,
t1.y
from table2 t2
left join table3 t3
on t2.id = t3.id
) input
set f1 = input.x
where f2 = input.y

Insert into with select

Insert into table1
(
field1,
field2,
field3
)
select
t2.x,
t2.y,
t3.x
from table2 t2
left join table3 t3
on t2.id = t3.id

Remove carriage returns from a field

select oTranslate(afield, '0A0D'xc,' ') from atable