在 MySQL 中使用 join 代替此子查询

Question

I have a table by the following structure and records, All i want to do is to just extract orderid of those records whose status id is either 1 or 2, i want to exclude all orderid with statusid=3, , problem is that orderid 106 has both status 1 and 3... I have written a sub-query which serves the purpose..

select * 
from orders_status_history 
where orders_id NOT IN 
   (select orders_id 
    from orders_status_history 
    where orders_status_id = 3)

is there any other way of doing this without using sub-queries as i have heard it hampers performance. As my query can return thousands of rows as well.

id    order-id    status-id
1     1            1
2     2            1
3     105          1
4     106          1
5     106          3
6     108          1
7     109          1
8     109          2

Any help or suggestion will be highly appreciated..Thanks in advance..

Answer 1

You may do that:

SELECT  osh.*
FROM    orders_status_history osh
LEFT JOIN
        orders_status_history oshd
ON      oshd.orders_id = osh_orders_id
        AND oshd.orders_status_id = 3
WHERE   oshd.orders_id IS NULL

However, if you have an index on order_status_history (orders_id, orders_status_id) , then the NOT IN query is just as fine.

You may want to read this:

• NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: MySQL

Answer 2

I wonder why you use sub query while you can use the following query

select orders_id from orders_status_history where orders_status_id <> 3

Please try this, and I hope it helps