我想查询 oracle 数据库以获取多个 case 子句的计数

Question

这是我正在尝试的查询：

SELECT DISTINCT(
  ( select distinct (
      (SELECT COUNT(*)  
       FROM PROCESS 
       WHERE STARTDATE > sysdate - INTERVAL '7' DAY) - 
      (SELECT COUNT(*) 
       FROM PROCESS 
       WHERE STARTDATE > sysdate - INTERVAL '14' DAY AND 
             STARTDATE < sysdate - INTERVAL '7' DAY)
  )as c3
  from process) /
  ( SELECT (CASE WHEN COUNT(*)=0 THEN (
      SELECT (case WHEN COUNT(*)=0 THEN 1  ELSE COUNT(*) end) 
      FROM PROCESS 
      WHERE STARTDATE > SYSDATE - INTERVAL '7' DAY  ) 
    ELSE COUNT(*) END)  
   FROM PROCESS 
   WHERE STARTDATE > SYSDATE - INTERVAL '14' DAY AND
         STARTDATE < SYSDATE - INTERVAL '7' DAY )
) AS ORDER_VOLUME FROM PROCESS;

但我收到此错误：

ORA-00937: not a single-group group function
00937. 00000 -  "not a single-group group function"
*Cause:    
*Action:
Error at Line: 1 Column: 295

谁能帮我解决这个问题？

这是我想要的

1) 获取 STARTDATE > SYSDATE - INTERVAL '14' DAY AND 的计数 STARTDATE SYSDATE - INTERVAL '14' DAY AND STARTDATE

如果在步骤 2) 中检索到的计数也为 0，则将计数设置为 1 else 设置检索到的计数

Answer 1

对我来说，这看起来像是一个 Oracle 错误。该查询在语法上似乎是正确的。

但是，您似乎并不确切地知道自己在做什么。该语句使用 DISTINCT 两次看起来很奇怪，当您人为地为表进程中的记录数重复一个值时，这绝对没有意义。

这就是您的查询将执行的操作，如果错误不会阻止此操作：

select
  (count_last_week - count_week_before_last_week) / 
  case 
    when count_week_before_last_week > 0 then  count_week_before_last_week
    when count_last_week > 0 then              count_last_week
    else                                       1
  end as order_volume
from
(
  select 
    sum(case when startdate > sysdate - interval '7' day then 1 end) as count_last_week,
    sum(case when startdate > sysdate - interval '14' day and startdate < sysdate - interval '7' day then 1 end) as count_week_before_last_week
  from process
);

检查这是否是您真正想要的，并在必要时修改此查询。

顺便说一句：请注意，您有 startdate > sysdate - interval '7' day 和 startdate < sysdate - interval '7' day，但没有 startdate = sysdate - interval '7' day。另外：您是故意考虑时间还是更愿意使用 trunc(startdate) 和 trunc(sysdate)？

Answer 2

'/'之后的这部分

SELECT  (
**--**CASE  WHEN COUNT()=0 THEN (
    SELECT  (
    case    WHEN COUNT()=0 THEN 1 
        ELSE    COUNT() 
    end ) 
FROM    PROCESS 
WHERE   STARTDATE > SYSDATE - INTERVAL '7' DAY ) 
ELSE    COUNT() 
END ) 

你不认为应该有一个选择，我将它标记为'--'你 innser sql 没有选择是错误的，或者只是删除那个括号并尝试像

SELECT  
CASE    WHEN COUNT()=0 THEN (
    SELECT  (
    case    WHEN COUNT()=0 THEN 1 
        ELSE    COUNT() 
    end ) 
FROM    PROCESS 
WHERE   STARTDATE > SYSDATE - INTERVAL '7' DAY ) 
ELSE    COUNT() 
END 
FROM    PROCESS**