select a.prod_code,a.prod_name ,b.prod_price,a.prod_custmoer_id,c.prod_customer_name fromproduct a left join prod_price b on a.prod_code=b.prod_codeleft join prod_customer c on a.prod_custmoer_id=b.prod_custmoer_id
select a.name,b.name,c.name from AA a left join BB b a.id=b.id where ... left join CC c a.id=c.id where ...
fromproduct a left join prod_price b on a.prod_code=b.prod_codeleft join prod_customer c on a.prod_custmoer_id=b.prod_custmoer_id
left join BB b a.id=b.id where ...
left join CC c a.id=c.id where ...