Forms :: Alpha Numeric Sequence Updating

We have document serial Nos increment program, which has the below query for selecting and Updating, which generates a Numeric Value;

Select Query:

Select doc_slno
from fin_jv_slno_mas
where jv_month = '05' and
jv_year = '2012'

Output of this Query: 800001

Update Query:

update fin_jv_slno_mas set doc_slno=docno+1 where
jv_year = '2012' and
jv_month = '05'

Output after Updation: 800002.

The above query is a normal Sequence updating for a Numeric Value; now we need to update it as Alpha Numeric as below

Example: 8A0001

How can we give the above update statement for Alpha Numeric updation?