查詢從表中

Question

hr_org有以下的列取只是一個項目： -

Org id Spoc Name 
123  HR A 
123  IT A 
123  VP A 
67  IT B 
78  HR C 
78  IT C 

我想創建一個查詢，其中只有那些名字都在其中僅IT SPOC定義。

對於如： -

select name 
from hr_org 
where SPOC ='IT' 

會給A和B 但對於其他SPOC（HR和VP）已經被推翻了爲好。我的輸出應該只取B.

Answer 1

select name 
from hr_org 
where SPOC ='IT' and name not in (select name from hr_org where SPOC<>'IT') 

Answer 2

select * 
from hr_org h1 
where spoc='IT' 
and not exists (
    select 1 
    from hr_org h2 
    where h2.spoc <> h1.spoc 
    and h2.name = h1.name 
)