R12 query to check Credit Limit of a customer

SELECT c.customer_number,c.customer_name,g.party_site_number,d.location,a.overall_credit_limit,
d.site_use_id,sum(e.amount_due_remaining) credit_balance
FROM   HZ_CUST_PROFILE_AMTS a, HZ_CUST_ACCOUNTS b, ar_customers c,
              hz_cust_site_uses_all d,ar_payment_schedules_all e,
              hz_cust_acct_sites_all f,hz_party_sites g
WHERE       overall_credit_limit IS NOT NULL
         and a.cust_account_id = b.cust_account_id
         and b.account_number = c.customer_number
         and a.site_use_id = d.site_use_id
         and c.customer_id = e.customer_id
         and d.site_use_id = e.customer_site_use_id
--         and c.customer_number = :customer_number
         and d.cust_acct_site_id = f.cust_acct_site_id
         and g.party_site_id = f.party_site_id
         and e.org_id = :org_id
GROUP BY c.customer_name,
c.customer_number,
d.site_use_id,
d.location,
a.overall_credit_limit,
g.party_site_number
ORDER BY CUSTOMER_NAME