Oracle SQL：即使特定值不存在也要返回记录

Question

我有一个查询，我试图从查询特定ID的表中提取一些值。如果该值不存在，我仍然希望查询返回一个只有该ID值的记录。这是迄今为止我尝试过的。

Select attr.attrval, attr.uidservicepoint, sp.servicepointid 
From bilik.lssrvcptmarketattr attr 
Join bilik.lsmarketattrtype type on attr.uidmarketattrtype = type.uidmarketattrtype AND 
type.attrtype IN ('CAPACITY_REQUIREMENT_KW') and TO_CHAR(attr.starttime , 'mm/dd/yyyy')in ('05/01/2011') 
Right Outer Join bilik.lsservicepoint sp on attr.uidservicepoint = sp.uidservicepoint 
Where sp.servicepointid in ('RGE_R01000051574382') Order By sp.servicepointid ASC 

在这个例子中，我试图寻找RGE_R01000051574382。如果表SP.servicepointid中不存在，我希望它仍然返回'RGE_R01000051574382'在一个记录中的空值，以表示我正在抽取的其他值。通常情况下，当我运行这个时，我将一次抽取大约1000个特定值。

如果有任何人有任何洞见，他们可以给予，这将不胜感激。非常感谢！

Answer 1

如果我理解正确，您只需要将WHERE子句移入JOIN子句。

select attr.attrval, 
    attr.uidservicepoint, 
    sp.servicepointid 
from bilik.lssrvcptmarketattr attr 
join bilik.lsmarketattrtype type on attr.uidmarketattrtype = type.uidmarketattrtype 
    and type.attrtype in ('CAPACITY_REQUIREMENT_KW') 
    and TO_CHAR(attr.starttime, 'mm/dd/yyyy') in ('05/01/2011') 
right outer join bilik.lsservicepoint sp on attr.uidservicepoint = sp.uidservicepoint 
    and sp.servicepointid in ('RGE_R01000051574382') 
order by sp.servicepointid 

Answer 2

我想你说你想有一个记录返回，与servicepointid列填充，但所有其他的空？

在这种情况下，请使用联合。

select ...your query without order by... 
and  sp.servicepointid = 'RGE_R010000515743282' 
union 
select null, null, 'RGE_R010000515743282' 
from  dual 
where not exists (select 'x' from (...your query without order by...)) 

这里有一个完整的例子：

create table test (id number, val varchar2(10)); 
insert into test (id, val) values (1, 'hi'); 

select id, 
     val 
from  test 
where id = 1 
union 
select 1, 
     null 
from  dual 
where not exists (select 'x' 
        from  test 
        where id = 1)