问题描述
如何在Oracle 11g中设计一个表，使其在以后与Oracle 12c中的新的时间有效性" 功能兼容?
How to design a table in Oracle 11g so that it is compatible later on with the new "Temporal validity" feature in Oracle 12c?
Oracle 12c的在线文档在SQL语言指南( http://docs.oracle.com/cd/E16655_01/server.121/e17209/statements_7002.htm#CJADHJHB )
The online documentation of Oracle 12c specifies how to define temporal validity inthe SQL Language guide (http://docs.oracle.com/cd/E16655_01/server.121/e17209/statements_7002.htm#CJADHJHB)
ALTER TABLE my_table ADD (PERIOD FOR my_valid_time (my_valid_start, my_valid_end) );
因此，人们可以使用11g中已经存在的旧的valid_from和valid_till列，并在12c中使用它们直到适当的时期，对吗?
So one could use the good old valid_from and valid_till columns already in 11g and beef them up to proper periods in 12c, right?
我继承了使用固定的魔术日期作为自始至终"和永远"的数据库，例如DATE '1900-01-01'和DATE '3999-12-31'.显然，12c改为使用NULL.
I've inherited databases that use fixed magic dates for "since always" and "for ever", for instance DATE '1900-01-01' and DATE '3999-12-31'. Apparently, 12c uses NULL instead.
那么，我们是否必须放弃使用固定的魔术日期并切换到NULL日期?
So, do we have to abandon using fixed magic dates and switch to NULL dates?
推荐答案
是的，您将能够更改12c中的表以启用时间有效性(请参见文档的ALTER TABLE部分: http://docs.oracle.com/cd/E16655_01/server.121/e17209/statement_3001.htm#CJAEGCFI )
Yes, you will be able to ALTER the table in 12c to enable Temporal Validity (see the ALTER TABLE section of the docs: http://docs.oracle.com/cd/E16655_01/server.121/e17209/statements_3001.htm#CJAEGCFI)
它通过将where子句转换为< =和">或为null"子句而起作用，因此，如果不需要，您无需更改固定日期.
It works by converting your where clause to a "<=" and "> or is null" clause, so you don't need to change the fixed dates if you don't want to.
汤姆·凯特(Tom Kyte)刚刚在他的博客上发布了有关此内容的文章，并列举了一些出色的例子: http://tkyte.blogspot.com /2013/07/12c-flashforward-flashback-or-see-it-as.html
Tom Kyte just posted on his blog about this today, with some execellent examples:http://tkyte.blogspot.com/2013/07/12c-flashforward-flashback-or-see-it-as.html
这篇关于如何在Oracle 12c中使用时间有效性?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！