Query to map values between tables

Question

Hi,
I'm trying to group data from the following three tables to create a new table.
Fields in bmf: account_no, trans_date
cmf: account_no, balance_due
acct_map: account_no, external_id
The fields I want in my new table are : external_id, account_no, balance_due.
When I use query 1, without the external_id column, it works fine and populates the data correctly. But when i try query 2, it creates a blank table. Will be great if anyone can point out my mistake and correct my query.
Many thanks!
novice.
Query 1:
create table paid as
select bmf.account_no, sum(cmf.balance_due) postpaid_balance
from bmf, cmf
where to_char(bmf.trans_date, 'YYYY MM DD') = '1996 08 14' and
bmf.account_no = cmf.account_no
group by bmf.account_no
Query 2:
create table paid as
select bmf.account_no, sum(cmf.balance_due) postpaid_balance, acct_map.external_id
from bmf, cmf, acct_map
where to_char(bmf.trans_date, 'YYYY MM DD') = '1996 08 14' and
bmf.account_no = cmf.account_no and
acct_map.account_no = bmf.account_no
group by bmf.account_no, acct_map.external_id

Answer 1

Sorry, perhaps i should have been more clear.
create table accounts (column1 number, .... etc);
insert into accounts () values (......);This allows users to see what your queries return, right now we have NO idea what your data looks like.
Also, expected output of your queries...you saying "it doesn't do what i want" doesn't help us much when we don't know what you want (this is where, using the sample data you provide to us, you show us what the result should be).
I'm not saying by any means you HAVE to do this, i'm just telling you that it's much more likely you'll get the help you are looking for if you do, that's all.
Try to put yourself in our shoes, being asked a question with no context, near no information and nothing to go on. Would you jump at the chance to guess and fumble around, or would you ask more questions to save time in the end?