如何只选择昨天的记录?

问题描述

我花了几个小时在网上搜索这个问题的答案......

I've spent hours searching the web for an answer to this question...

这是我目前拥有的:

select  *
from    order_header oh
where   tran_date = sysdate-1

推荐答案

使用:

AND oh.tran_date BETWEEN TRUNC(SYSDATE - 1) AND TRUNC(SYSDATE) - 1/86400

参考:TRUNC

在 tran_date 上调用函数意味着优化器将无法使用与其关联的索引(假设存在索引).某些数据库(例如 Oracle)支持基于函数的索引，这些索引允许对数据执行函数以最大程度地减少这种情况下的影响，但 IME DBA 不允许这样做.我同意 - 在这种情况下它们并不是真正必要的.

Calling a function on the tran_date means the optimizer won't be able to use an index (assuming one exists) associated with it. Some databases, such as Oracle, support function based indexes which allow for performing functions on the data to minimize impact in such situations, but IME DBAs won't allow these. And I agree - they aren't really necessary in this instance.

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