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Question

我想联合2查询，但在oracle中遇到错误。

select count(*) as faultCount,
       COMP_IDENTIFIER 
from CORDYS_NCB_LOG 
where AUDIT_CONTEXT='FAULT' 
union 
select count(*) as responseCount,
       COMP_IDENTIFIER 
from CORDYS_NCB_LOG 
where AUDIT_CONTEXT='RESPONSE' 
group by COMP_IDENTIFIER  
order by responseCount; 

两个查询可以完美地独立运行。但是使用联合时，它会显示ORA-00904：“ RESPONSECOUNT”：无效的标识符

Answer 1

您遇到的错误

在Oracle中，最好始终以UNION相同的方式命名每个子查询中的每个列。在您的情况下，以下应该起作用：

select count(*) as theCount,
       COMP_IDENTIFIER 
from CORDYS_NCB_LOG 
where AUDIT_CONTEXT='FAULT' 
group by COMP_IDENTIFIER -- don't forget this
union 
select count(*) as theCount,
       COMP_IDENTIFIER 
from CORDYS_NCB_LOG 
where AUDIT_CONTEXT='RESPONSE' 
group by COMP_IDENTIFIER  
order by theCount; 

也可以看看：

Oracle UNION和ORDER BY的奇怪问题

当然，一个好的解决方法是使用a_horse_with_no_name建议的索引列引用

您真正想要的查询

但是，从您的评论中，我怀疑您想编写一个完全不同的查询，即：

select count(case AUDIT_CONTEXT when 'FAULT'    then 1 end) as faultCount,
       count(case AUDIT_CONTEXT when 'RESPONSE' then 1 end) as responseCount,
       COMP_IDENTIFIER 
from CORDYS_NCB_LOG 
where AUDIT_CONTEXT in ('FAULT', 'RESPONSE')
group by COMP_IDENTIFIER  
order by responseCount;