Finding dates when accounts reach zero - sql

Question

Thanks for taking the time to examine my issue.
I'm trying to figure out a way to return dates when an account reaches 0
Sample data:
DATE ACCOUNT AMOUNT
11/01 001 100
11/02 002 50
11/03 001 -100
11/07 001 20
11/15 002 -50
11/20 001 -20
Wanted results:
Account ZeroDate
001 11/03
002 11/15
001 11/20
So far I haven't been able to figure out anything that works. Might you be able to point me in the right direction?
Thanks again in advance!

Answer 1

You can use analytic functions to compute the running balance
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select date '2011-11-01' dt, 1 account, 100 amt from dual union all
3 select date '2011-11-02', 2, 50 from dual union all
4 select date '2011-11-03', 1, -100 from dual union all
5 select date '2011-11-07', 1, 20 from dual union all
6 select date '2011-11-15', 2, -50 from dual union all
7 select date '2011-11-20', 1, -20 from dual
8 )
9 select dt,
10 account,
11 amt,
12 sum(amt) over (partition by account order by dt) current_balance
13* from x
SQL> /
DT ACCOUNT AMT CURRENT_BALANCE
--------- ---------- ---------- ---------------
01-NOV-11 1 100 100
03-NOV-11 1 -100 0
07-NOV-11 1 20 20
20-NOV-11 1 -20 0
02-NOV-11 2 50 50
15-NOV-11 2 -50 0
6 rows selected.
and then use the running balance to find the zero dates.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select date '2011-11-01' dt, 1 account, 100 amt from dual union all
3 select date '2011-11-02', 2, 50 from dual union all
4 select date '2011-11-03', 1, -100 from dual union all
5 select date '2011-11-07', 1, 20 from dual union all
6 select date '2011-11-15', 2, -50 from dual union all
7 select date '2011-11-20', 1, -20 from dual
8 )
9 select account,
10 dt zero_date
11 from (
12 select dt,
13 account,
14 amt,
15 sum(amt) over (partition by account order by dt) current_balance
16 from x
17 )
18* where current_balance = 0
SQL> /
ACCOUNT ZERO_DATE
---------- ---------
1 03-NOV-11
1 20-NOV-11
2 15-NOV-11

Answer 2

create table myacct (dt varchar2(5)
, account varchar2(3)
, amount number
)
;
insert into myacct values ('11/01', '001', 100);
insert into myacct values ('11/02', '002', 50);
insert into myacct values ('11/03', '001', -100);
insert into myacct values ('11/07', '001', 20);
insert into myacct values ('11/15', '002', -50);
insert into myacct values ('11/20', '001', -20);
commit;
/* results wanted:
Account ZeroDate
001 11/03
002 11/15
001 11/20 */
select account "Account", dt "ZeroDate"
from myacct
where amount <= 0
;
/* results from above query:
Account ZeroDate
001 11/03
002 11/15
001 11/20
*/