Cómo obtener la fecha diff en el campo una vez en SQL Server
SELECT t1.OrderNo,DATEDIFF(day,t1.LoadedStartDate,t2.LoadedStartDate)
FROM UnnamedTableFromQuestion t1
INNER JOIN
UnnamedTableFromQuestion t2
on
t1.OrderNo = t2.OrderNo
WHERE t1.OpNo = 1 and
t2.OpNo = 4
////////////////////////////////////////////////////////////////
select cur.unique_id_field, cur.seq_no, cur.date_created ,
datediff(second, prv.date_created, cur.date_created) as diff_in_seconds
from yourtable as cur
join yourtable as prv
on cur.seq_no = prv.seq_no + 1;
Kandyman