sql - 选择一个计数和一个大于一的最大值的计数

Question

我有一个查询需要计算一些列的一些计数和一列的最大值的计数，然后按更多标准分组。

到目前为止，我有以下查询：

select 
subj.inventoryNum as Inventory,
extract(month from subj.createDate) as month,
oolame.schoolCode as Code,
count(case when max(subVers.verNum) > 0 then 1 end) as deleted,
count(case when subVers.delDate is not null then 1 end) as changed

from 
Subjects subj
inner join SubjectVersions subVers on subVers.subjFk = subj.subjId
inner join SchoolName oolame on oolame.oolameId = subj.oolameFk 

group by 
subj.inventoryNum,
extract(month from subj.createDate),
oolame.schoolCode;

它给了我以下错误：

ORA-00937: not a single-group group function
00937. 00000 -  "not a single-group group function"
*Cause:    
*Action:
Error at Line: 2 Column: 1

Answer 1

你想做什么有点不清楚。你想要整体最大值吗？每个科目的最大值？其他一些最大值？

在任何情况下，您都可以在子查询中使用窗口函数来获取最大值。例如，如果您想要每个主题的最大值：

select subj.inventoryNum as Inventory,
       extract(month from subj.createDate) as month,
       oolame.schoolCode as Code,
       sum(case when subVers.max_verNum > 0 then 1 else 0 end) as deleted,
       count(subVers.delDate) as changed
from Subjects subj inner join
     (select subvers.*,
             max(subVers.verNum) over (partition by subVers.subjFk) as max_verNum
      from SubjectVersions subVers
     ) subVers
     on subVers.subjFk = subj.subjId inner join
     SchoolName oolame
     on oolame.oolameId = subj.oolameFk 
group by subj.inventoryNum,
         extract(month from subj.createDate),
         oolame.schoolCode;