LEFT JOIN ($sales_credit) AS sales_credit USING (billpkgnum)
LEFT JOIN ($exempt_credit) AS exempt_credit USING (billpkgnum, taxnum)
$join_cust_pkg $where AND $nottax
LEFT JOIN ($sales_credit) AS sales_credit USING (billpkgnum)
LEFT JOIN ($exempt_credit) AS exempt_credit USING (billpkgnum, taxnum)
$join_cust_pkg $where AND $nottax
LEFT JOIN ($exempt_credit) AS exempt_credit USING (taxnum)
JOIN cust_bill_pkg USING (billpkgnum)
$join_cust_pkg $where AND $nottax
LEFT JOIN ($exempt_credit) AS exempt_credit USING (taxnum)
JOIN cust_bill_pkg USING (billpkgnum)
$join_cust_pkg $where AND $nottax