SQL：对表分区进行交叉联接

Question

我有下表

session_id | page_viewed
    1      |     A
    1      |     B
    1      |     C
    2      |     B
    2      |     E

我想做的是将page_viewed列与其自身进行交叉联接，但是在session_id的分区上进行交叉联接。因此，从上面的表中查询将返回：

session_id | page_1 | page_2
    1      |    A   |   A
    1      |    A   |   B
    1      |    A   |   C
    1      |    B   |   A
    1      |    B   |   B
    1      |    B   |   C
    1      |    C   |   A
    1      |    C   |   B
    1      |    C   |   C
    2      |    B   |   B
    2      |    B   |   E
    2      |    E   |   B
    2      |    E   |   E

我今天研究了窗口函数，试图找到解决方法，但是似乎无法使用join函数。有人可以帮忙吗？

Answer 1

嗯。 。 。您似乎想要自我加入：

select t1.session_id, t1.page_viewed as page_1, t2.page_viewed as page_2
from t t1 join
     t t2
     on t1.session_id = t2.session_id
order by t1.session_id, t1.page_viewed, t2.page_viewed;

Answer 2

您可以加入session_id作为加入条件：

SELECT
    t1.session_id,
    t1.page_viewed AS page_1,
    t2.page_viewed AS page_2
FROM yourTable t1
INNER JOIN yourTable t2
    ON t1.session_id = t2.session_id;
-- ORDER BY clause optional, if you need it here

Demo