如何在不重复的情况下重用大型查询? [英] How to reuse a large query without repeating it?

问题描述

如果我有两个查询，分别称为horrible_query_1和ugly_query_2，我想对它们执行以下两个减号操作:

If I have two queries, which I will call horrible_query_1 and ugly_query_2, and I want to perform the following two minus operations on them:

(horrible_query_1) minus (ugly_query_2)
(ugly_query_2) minus (horrible_query_1)

或者我有一个terribly_large_and_useful_query，它产生的结果集我想用作以后的几个查询的一部分.

Or maybe I have a terribly_large_and_useful_query, and the result set it produces I want to use as part of several future queries.

如何避免在多个位置复制和粘贴相同的查询?我如何不重复自己"并遵循DRY原则.在SQL中可以吗?

How can I avoid copying and pasting the same queries in multiple places? How can I "not repeat myself," and follow DRY principles. Is this possible in SQL?

我正在使用Oracle SQL.首选便携式SQL解决方案，但如果我必须使用Oracle特定功能(包括PL/SQL)，那就可以了.

I'm using Oracle SQL. Portable SQL solutions are preferable, but if I have to use an Oracle specific feature (including PL/SQL) that's OK.

推荐答案

create view horrible_query_1_VIEW as 
 select .. ...
  from .. .. ..

create view ugly_query_2_VIEW as 
 select .. ...
  from .. .. ..

然后

(horrible_query_1_VIEW) minus (ugly_query_2_VIEW)

(ugly_query_2_VIEW) minus (horrible_query_1_VIEW)

或者，也许使用with clause:

with horrible_query_1 as (
  select .. .. ..
    from .. .. ..
) ,
ugly_query_2 as (
  select .. .. ..
     .. .. ..
)
(select * from horrible_query_1 minus select * from ugly_query_2    ) union all
(select * from ugly_query_2     minus select * from horrible_query_1)

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