如何選擇不具有特定列值的項目？

Question

我的數據是這樣的：

group_id | meta_key | meta_value 
---------------------------------------- 
    33 | has_foo | definitely_has_foo 
    33 | is_bar | might_be_bar 
    33 | a_key | a_value 
    65 | has_foo | probably 
    86 | something| something_else 

我想選擇所有group_id s表示不有meta_key稱爲has_foo，在這種情況下會86。有沒有辦法做到這一點？

Answer 1

select group_id 
from your_table 
group by group_id 
having sum(meta_key = 'has_foo') = 0 

Answer 2

SELECT group_id 
FROM T 
WHERE group_id NOT IN (SELECT group_id FROM T WHERE meta_key = 'has_foo')