Oracle Query 根据结果集中的值获取单个结果

Posted 2023-05-09

【中文标题】Oracle Query 根据结果集中的值获取单个结果

【英文标题】：Oracle Query to get single result depending on values in result set

【发布时间】：2020-07-20 10:40:52

【问题描述】：

WITH T1 AS SELECT DISTINCT(DETAILS) FROM ( SELECT STATUS, PREREQUISITE_NM, 
    (case  when (STATUS='Completed' ) then 'Completed'
    when (STATUS='Pending' ) then 'Pending'
    when (STATUS='Failed' and PREREQUISITE_NM = 'Y') then 'Failed'
    when (STATUS='Failed' and PREREQUISITE_NM = 'N') then 'Completed'
    end )DETAILS FROM TABLE_LIST WHERE ID=1))
    T2 AS ( SELECT DETAILS FROM T1)

结果 1： 待定 失败 已完成。结果 2： 失败 已完成。

在上面的查询中，我们根据可用数据看到不同的结果集。我想在 T2 Block 中写一个查询，它应该输出为：

对于 Pending/Failed/Completed：应该将 Pending 作为输出。 对于失败/完成：应将失败作为输出。 是否可以在不使用 PL SQL 块的情况下通过查询来实现这一点。喜欢用 WITH 子句？

我可以解释我的目标，例如

假设 T1 Block 给我的结果是三行 Pending、Failed、Completed 然后我希望 Pending 作为输出值。如果 T1 Block 给我的结果是 Failed, Completed 那么我想 Failed 作为输出值。如果 T1 块仅给出 Completed，则 Completed 将被视为输出值。

【问题讨论】：

你想同时得到两个结果吗？？

假设 T1 Block 给我的结果是三行 Pending、Failed、Completed 然后我希望 Pending 作为输出值。如果 T1 Block 给我的结果是 Failed, Completed，那么我想 Failed 作为输出值。如果 T1 块仅给出 Completed，则 Completed 将被视为输出值。

我发了一个答案，请在那里跟进

【参考方案1】：

感谢 Roberto 和 Barbaros Ozhan，两个答案都很有用。发布我的一位同事分享的另一种方式。

WITH T1 AS (
SELECT
DISTINCT(DETAILS) 
FROM (
  SELECT STATUS, PREREQUISITE_NM, 
 (
CASE 
WHEN (STATUS = 'Failed' ) THEN
           CASE WHEN PREREQUISITE_NM = 'Y' THEN 'Failed' 
                WHEN PREREQUISITE_NM = 'N' THEN 'Completed' 
           END 
         ELSE 
           STATUS
           END
)DETAILS FROM TABLE_lIST WHERE ID=1)
),
T2 AS
(
SELECT CASE 
WHEN EXISTS
( SELECT DETAILS FROM  T1 where DETAILS='Pending' )
THEN 'Pending'  
WHEN EXISTS
( SELECT DETAILS FROM T1 WHERE DETAILS='InProgress' )
THEN 'InProgress'  
WHEN EXISTS
(SELECT DETAILS FROM T1 where DETAILS='Failed' )
THEN 'Failed'  
ELSE 'Completed' END  as DETAILS from DUAL 
                 )SELECT * FROM T2

【参考方案2】：

您可以使用ROW_NUMBER() Analytic 函数将这些状态值按字母顺序降序排列，以满足您的需要：

WITH T1 AS
(
SELECT DISTINCT (CASE
         WHEN (STATUS = 'Failed' ) THEN
           CASE WHEN PREREQUISITE_NM = 'Y' THEN 'Failed' 
                WHEN PREREQUISITE_NM = 'N' THEN 'Completed' 
           END 
         ELSE 
           STATUS 
         END) AS details
  FROM TABLE_LIST
 WHERE ID = 1
), T2 AS
(
 SELECT T1.*, ROW_NUMBER() OVER (ORDER BY details DESC) AS rn
   FROM T1
 )   
SELECT details
  FROM T2
 WHERE rn = 1 

【讨论】：

感谢您的回复。但正如我提到的，我只想返回一个值。根据我们在查询输出中获得的值，可能是 Pending、Failed 或 Completed。

非常感谢。查询正在使用可用状态。

【参考方案3】：

在阅读了您的 cmets 之后，我想出了这个解决方案，这可能不是最好的，但最后给出了您期望的输出，基于您真正想要的是将 t1 中生成的行转换为t2

我使用自己的测试，请注意替换列或修改任何必要的内容以使其适应您自己的查询

SQL> desc my_test
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 NUMBER
 C2                                                 VARCHAR2(20)
 C3                                                 VARCHAR2(1)

SQL> select * from my_test ;

        C1 C2                   C3
---------- -------------------- -
         1 Failed               Y
         2 Completed            Y
         1 Pending              Y
         1 Pending              N

SQL>

所以，如果刚刚得到我的查询的第一部分

SQL> WITH T1 AS (
     SELECT DISTINCT c2 FROM ( SELECT c1,c2,
     case  when c2='Completed'  then 'Completed'
           when c2='Pending'    then 'Pending'
           when c2='Failed' and c3 = 'Y' then 'Failed'
           when c2='Failed' and c3 = 'N' then 'Completed'
           else c2
           end FROM my_test WHERE c1=1
                 ) )
select trim ( completed || ' ' || failed || ' ' || pending ) as result
from
(
select * from t1 pivot ( max(c2) for c2 in ( 'Completed' as Completed, 'Failed' as Failed, 'Pending' as Pending ) )
)
/  9   10   11   12   13   14   15

RESULT
--------------------------------------------------------------
Failed Pending

现在我只需要在该结果上构建一个案例（根据您自己的要求修改它）

SQL> WITH T1 AS (
            SELECT DISTINCT c2 FROM ( SELECT c1,c2,
                                                                                        case  when c2='Completed'  then 'Completed'
                                                  when c2='Pending'    then 'Pending'
                                                  when c2='Failed' and c3 = 'Y' then 'Failed'
                                                  when c2='Failed' and c3 = 'N' then 'Completed'
                                                                                        else c2
                                                                                        end FROM my_test WHERE c1=1
                 ) ) 
select 
case when result = 'Completed Failed Pending' then 'Pending' 
     when result = 'Completed Failed'         then 'Failed' 
     when result = 'Failed Pending'           then 'Failed' -- I guess
     when result = 'Completed Pending'        then 'Pending' -- I guess
end as output 
from (       
select trim ( completed || ' ' || failed || ' ' || pending ) as result 
from 
(                
select * from t1 pivot ( max(c2) for c2 in ( 'Completed' as Completed, 'Failed' as Failed, 'Pending' as Pending ) )
)
)
/

OUTPUT
-------
Failed

SQL>

【讨论】：

非常感谢。我会尝试给定的解决方案，并会更新你。