Maybe have another table that defines your status codes.
e.g
tblStatus
statusId
statusCode
statusOrder
Your records could be defined as
statusId statusCode statusOrder
1 D 3
2 A 2
3 P 1
4 R 4
Then you can just use standard SQL and join the tables + use an order by on the statusOrder column
select * from tblcomp C inner join tblStatus S on C.sts = S.statusCode ORDER BY statusOrder
If you're going to do this, better to store the ID from tblStatus in tblComp rather than the status code - but the above demonstrates the technique