如何讓sql查詢「不在」更簡單地只使用「join」？

Question

有無查詢：

select a.id from selzde.elorder a 
inner join selzde.elorder b on a.name = b.name 
    and a.workname = b.workname 
    and b.id = needId 
where a.id not in (select id_elorder from selzde.drugselorder) 

如何使SQL查詢not in更簡單地只使用join？

Answer 1

select a.id from selzde.elorder a 
inner join selzde.elorder b on a.name = b.name 
and a.workname = b.workname 
and b.id = needId 
left outer join selzde.drugselorder d on a.id = d.id_elorder 
where d.id_elorder is null 

Answer 2

LEFT JOIN到drugselorder，在id_elorder = a.id，然後選擇與不匹配（即where drugselorder is null）中的那些......我不會說這是更多的「簡單」，雖然。

Answer 3

一個解決辦法是使用減號運營商，而不是不如下：

select a.id 
from selzde.elorder a 
    inner join selzde.elorder b 
on a.name = b.name  
and a.workname = b.workname  
and b.id = needId 
MINUS 
select id_elorder 
from selzde.drugselorder 
; 

希望這有助於。

Regards， Roger