left semi join 的結果只返回左表的列壁却，右表只能放在 join condition 中用于過濾判斷，可以理解為 in 的替代品
select *
from a left semi join b
on a.id = b.id
--- 等價于
select *
from a
where a.id in
(select b.id from b)
left anti join 與 left semi join 相反谓娃，返回不滿足 join condition 的結果，可以理解為 not in 的替代品
select *
from a left anti join b
on a.id = b.id
--- 等價于
select *
from a
where a.id not in
(select b.id from b)
