Customer list who have a balance

Dear All,

im trying to build a query that select the customer list & what currency they have

but it takes too much time , im not sure how i can optimize it because when i want to  run it to select all customer and im dont know waht to do to remove the UNION & UNION ALL

the procedure is as below :

CREATE OR REPLACE PROCEDURE XX_CUST_CURLIST(  P_ORG_ID number ,P_CUSTOMER_NUM char,  p_currency_code char , P_TRX_FROM_DATE char  ,P_TRX_TO_DATE char ) IS

cust_num varchar2(100);

cust_name varchar2(100);

cust_curr   varchar2(100);

k number(38) :=0;