联结查询条件的多样化使用！

[Sorder]

不知道各位同仁在涉及到查询的时候有没有遇到下列语句：
表A，B
select * from A join B on A.id=B.id where A.amount>0
select * from A join B on A.id=B.id and A.amount>0

select * from A left join B on A.id=B.id where A.amount>0
select * from A lef join B on A.id=B.id and A.amount>0

select * from A right join B on A.id=B.id where A.amount>0
select * from A right join B on A.id=B.id and A.amount>0

select * from A full outer join B on A.id=B.id where A.amount>0
select * from A full outer join B on A.id=B.id and A.amount>0

各位可以谈谈自己在用到这些SQL语句的问题