Select Max

Can anyone help me in this problem?

At table do_master, there are a field "do_no", the data is like :
D0400001
D0400003
D0400004
D0400005
D0400006

String sqldono = "SELECT convert(int,(SUBSTRING(do_no,4,8))) AS do1 FROM do_master WHERE (SUBSTRING(do_no,1,3))='D04' ORDER BY do_no";


The result is
00001
00003
00004
00005
00006

I would like to get the max, that is 00006.

String sqldono = "SELECT MAX(convert(int,(SUBSTRING(do_no,4,8)))) AS do1 FROM do_master WHERE (SUBSTRING(do_no,1,3))='D04' ORDER BY do_no";

It is not work..

Any error for sqldono above?

Thanks~~

try this:

SELECT SUBSTRING(do_no,4,8)
FROM do_master
WHERE (SUBSTRING(do_no,1,3))='D04' AND convert(int,(SUBSTRING(do_no,4,8)))= (SELECT MAX(convert(int,(SUBSTRING(do_no,4,8)))) AS do1
FROM do_master
WHERE (SUBSTRING(do_no,1,3))='D04')

Basicaly I did a subquery(the second select) to get the Max of do_no then I compare the table to get the record with has a 6 for the expression convert(int,(SUBSTRING(do_no,4,8)))

Ouput
-----
0006