SQL查詢來從一個表是不是在另一個表

Question

Registraion和group_members

Registration Table 
id name 
-------     
1 A  
2 B  
3 C 
4 D 

group_members Table 
name Gid 
-------     
A 01  
B 01  
C 02 

我需要從註冊表，該表是不是在group_members成員獲得名稱中選擇行表Gid是02。 輸出必須明顯爲A，B和D。 但我不知道如何實現this.Please help.Thanks

Answer 1

試試這個：

SELECT t1.* 
FROM Registration AS t1 
LEFT JOIN Group_members AS t2 ON t1.name = t2.name AND t2.Gid = '02' 
WHERE t2.name IS NULL 

這將在group_members表中篩選出所有符合的記錄與Gid = '02'。

Answer 2

這應該工作

select name from 
Registration reg where 
not exists 
(select null 
from group_members gm 
where gm.name = reg.name 
and gm.gid = '02')