subquery

Hi All,

There are two rows in the table, one is the discount record, one is the normal amount. Data as below:

txn_id txn_typedocket_voucher_numberamt ...

121113226 5 002712 86.88

121116789 2 002712-3.41

I want to use subquery the table by taking the two amts (both '86.88' and '-3.41')

expected return result should be:

txn_id txn_typedocket_voucher_numberamt discount_amt

121113226 5 002712 86.88 -3.41

I had the following query which is not working at the moment:

select txn_id,

 txn_type,

docket_voucher_number,

amt,

(select tn.amt 

from txn tn 

where tn.docket_voucher_number = t.docket_voucher_number) discount_amt

from  txn t

INNER JOINcons_chain_tab cct

ONt.cust_id= cct.cust_id

INNER JOIN cust_fin cf

ONcct.account_cust_id = cf.cust_id

ANDt.txn_type=5

ANDt.system_date_loaded >= '20100517'

AND t.system_date_loaded < '20100617'

WHEREcf.plan_id='CX'

Please help with this. It's quite urgent.

Cheers,

Chris