updating null records in a table

Hii,
I have created a check writing program which consists of a table
name "DATA" with fields CHECKNO, CHECKDT, BANKNAME & AMOUNT & also a
query with date criteria with the above fields. I have 2 problems while
generating reports
1. I have created a report based on the above query with criteria
set to CHECKNO Is null the problem is that while entering data into
table i will enter all the fields except "CHECKNO". Checkno should be
prompted when the checks to be printed & same time checkno to be
updated sequentially in "DATA" table.
2. "BANKNAME" consists of atleast 3 banks for which a different
series of checkno is used, for which each time as an when bankname
changes in report,report should prompt for fresh starting chequeno & it
should be incremented sequentially.
3. If any check is cancelled or printed wrong then particular check
is destroyed & fresh checkno is alloted
Any help on VBA function for this, and also how implemnet the
function in ms access as iam new to access modules.
Thank you.

re: updating null records in a table

Use DMAX to get the next check number for each account. normally this
is done when the records are created, but I suppose you could request
just before printing. And then just after the printing, ask if the
checks all printed correctly. Any that do not print correctly, will
get voided and reprinted.