sql - SQL 查询 pubs 数据库的 order 上有多个 title 的 store

Question

在pubs数据库中，我想找出订单上有多个标题的商店。我已加入表格，但我无法理解用于查找具有多个标题的订单的逻辑

SELECT 
    title, stores.stor_name, S.ord_num, S.qty
FROM 
    sales S
JOIN
    titles T ON (S.title_id = T.title_id)
JOIN
    stores ON (S.stor_id = stores.stor_id)

在此处输入图像描述

Answer 1

就像是

    SELECT 
    title, stores.stor_name, S.ord_num, S.qty
FROM 
    sales S
JOIN
    titles T ON (S.title_id = T.title_id)
JOIN
    stores ON (S.stor_id = stores.stor_id)
where S.ord_num in (

    SELECT 
    S1.ord_num
FROM 
    sales S1
JOIN
    titles T1 ON (S1.title_id = T1.title_id)
JOIN
    stores  st ON (S1.stor_id = st.stor_id)
    group by S1.ord_num
    having count( distinct title)>1
    )