Oracle-子查询与分析函数查询

问题描述

-- One
select * from
(select
    employeeid, effectivedate, designationid,
    max(effectivedate) over (partition by employeeid) meffectivedate
from
    designationtransfers
) where effectivedate = meffectivedate

-- Two
select employeeid, effectivedate, designationid from
	designationtransfers t
where
	effectivedate =
		(select max(effectivedate) from designationtransfers t1 where t.employeeid = t1.employeeid)

上面两个查询的结果是相同的.但是，我不确定哪个是要使用的，哪个要优于另一个.

有人可以帮我吗?

预先谢谢您.

The result of the above two queries is the same. But, I am uncertain which is the one to use and which is better than the other.

Can anybody help me?

Thank you in advance.

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