一个查询优化的有关问题

一个查询优化的问题
现在有3各表或者视图 a,b,c,d都有一个字段code，现要查找a中code同时在b,c,d中的记录
是用多个in子查询号还是先讲b,c,d inner join了好？如下：

方案1:
select code from a where 
code in (select code from b) and
code in (select code from c) and
code in (select code from d)

方案2:
select code from a where code in (
select b.code from b,c,d where b.code=c.code and b.code=d.code)

方案3:
select code from a where code in (
select t1.code from (select b.code from b) t1
inner join (select c.code from c) t2 on t1.code=t2.code
inner join (select d.code from d) t3 on t1.code=t3.code
)

请教下三个方案的优缺点及执行流程。



------解决方案--------------------

SQL code

select a.code from a join (select b.code from b,c,d where b.code=c.code and b.code=d.code) t        on a.code = t.code
------解决方案--------------------
SQL code
select distinct a.code from a,b,c,d where a.code=b.code and b.code=c.code and b.code=d.code
------解决方案--------------------
SQL code
select a.*from ainner join b on a.code=b.codeinner join c on a.code=c.codeinner join d on a.code=d.code
------解决方案--------------------
探讨


SQL code

select a.*
from a
inner join b on a.code=b.code
inner join c on a.code=c.code
inner join d on a.code=d.code