Monthly GL balances Query

I am working on a query to retrieve GL balances for the month the query is run.

This should include the company code, GL account, GL text, year, period, GL balance for the corresponding period and currency. The should be capable of getting upto date balances of the month selected. Even if run on the specific day of a month should provide with the total balances from the beginning of the month until that day. Only one month should be displayed at a time. My Question is how to get the balances for each month What tables should I use etc,

for example

abcd 12000 bank account 2007 03 12125.00 USD

Any clarification is appreciated.

Thanks

krishna