mysql 联表查询

Question

A表        order_id         data
             1                 1
             2                 2
             3                 3

B表        order_id         state
             1                1
             2                2
             
             
             

查找A中与B不重复的对应order_id的data（即order_id=3的data），sql语句怎么写？

Answer 1

select data from a 
where order_id not in (
  select distinct order_id from b 
);

Answer 2

select data
from A left join B on A.order_id = B.order_id
where isnull(B.state)

Answer 3

select * from A where order_id not in (select order_id from B)

Answer 4

SELECT a.data FROM a LEFT JOIN b ON a.order_id=b.order_id WHERE b.order_id IS NULL

Answer 5

select data from A where A.id not IN (select B.id from B)

Answer 6

select data from a where not exists (select 1 from b where a.order_id = b.order_id)