如何把下面的mysql语句转化为oracle语句 ？

SELECT
count( t2.credit_no ) company_count,
IFNULL( sum( t3.total_taxes ), 0 ) AS total_tax,
IFNULL( sum( t3.income ), 0 ) AS total_sale
FROM
unicde_land_block t1
JOIN (
SELECT * FROM unicde_company_block GROUP BY credit_no, belong_year, belong_month
) t2 ON t1.cadastre = t2.cadastre
AND t1.belong_month = t2.belong_month
AND t1.belong_year = t2.belong_year
JOIN unicde_company_info t3 ON t2.credit_no = t3.credit_no
AND t2.belong_month = t3.belong_month
AND t2.belong_year = t3.belong_year
WHERE
1=1

https://blog.csdn.net/qq_41622282/article/details/99689319

SELECT
count( t2.credit_no ) company_count,
NVL( sum( t3.total_taxes ), 0 ) AS total_tax,
NVL( sum( t3.income ), 0 ) AS total_sale
FROM
unicde_land_block t1
JOIN (
SELECT * FROM unicde_company_block GROUP BY credit_no, belong_year, belong_month
) t2 ON t1.cadastre = t2.cadastre
AND t1.belong_month = t2.belong_month
AND t1.belong_year = t2.belong_year
JOIN unicde_company_info t3 ON t2.credit_no = t3.credit_no
AND t2.belong_month = t3.belong_month
AND t2.belong_year = t3.belong_year
WHERE
1=1