1

我正在尝试制作一个在两个值之间“存储”解码的子表，因为我需要多次使用该解码。假设这些是我的表：

Table Person
Name    Number_name
Jeremy  One
Thomas  Two
Stephen Three

我当前的 SQL 如下所示：

SELECT
    decode (number_name,
    'one',1,
    'two',2,
    'three',3,
    'four',4)
    num
    FROM person where name = 'Jeremy'
    and (some other condition)
UNION SELECT
    decode (number_name,
    'one',1,
    'two',2,
    'three',3,
    'four,4)
    num
    FROM Person
    where Name <> "Jeremy"
    and (some other condition)

我想做的是这样的：

SELECT num from my_temp_table where name = "Jeremy" and (some other condition)
union select num from my_temp_table where name <> "Jeremy" and (some other condition)
...

在该查询期间构造 my_temp_table 的位置（当查询完成运行时它不再存在）并且看起来像

Table my_temp_table
Name  num
One   1
Two   2
Three 3
Four  4

并且希望我可以在没有“选择一个名称，1 个来自双重联合的所有...”的情况下做到这一点

这是可行的吗？

4

1 回答 1

5

该WITH条款听起来与您所描述的最接近。但这需要您以某种方式生成数据。选择DUAL可能是最简单的选择

WITH my_temp_table AS (
  SELECT 'One' name, 1 num from dual union all
  SELECT 'Two', 2 from dual union all
  SELECT 'Three', 3 from dual union all
  SELECT 'Four', 4 from dual
)
SELECT *
  FROM my_temp_table 
       JOIN person ON (<<some join condition>>)
 WHERE <<some predicate>>

由于您不想合并一堆查询，因此您可以执行类似的操作

WITH my_temp_table AS (
  select level num,
         initcap( to_char( to_date( level, 'J' ),
                           'JSP' )) name
    from dual
 connect by level <= 4
)
...
于 2012-05-24T02:43:08.583 回答