SQL 笛卡尔类型连接

Question

我有 2 个表（针对此示例进行了简化），我想以特定方式加入它们。

Table 1（ae）有科目编号，ae term
Table 2 (mh) 有科目编号，mh term

这里的结构可以提供帮助

INSERT INTO ae VALUES ('0001-0012','DRY EYE (12 OCT 2017)');
INSERT INTO ae VALUES  ('0001-0012', 'DEPRESSION (7 OCT 2017)');
INSERT INTO ae VALUES ('0001-0013','SKIN ATROPHY, LEFT UPPER ARM (4 OCT 2017 )');


INSERT INTO mh VALUES ('0001-0012', 'DIABETES MELLITUS (UN JUL 2007)');
INSERT INTO mh VALUES ('0001-0012', 'GASTRO-ESOPHAGEAL REFLUX INTERMITENT GR1 (18 AUG 2017)');
INSERT INTO mh VALUES ('0001-0012', 'ESOPHAGITIS GR 1 (18 AUG 2017)');
INSERT INTO mh VALUES ('0001-0012', 'DIARRHEA INITERMITTENT GR2 (5 JUL 2017 )');
INSERT INTO mh VALUES ('0001-0012', 'FATIGUE INTERMITTENT GR1 (18 AUG 2017)');
INSERT INTO mh VALUES ('0001-0013', 'VOMITING, INTERMITTENT GR1 (6 JUL 2017 )');

我希望我的输出看起来像这样：

有什么帮助吗？如您所见，我需要一个粗糙的连接！

Answer 1

您可以使用 row_number() 和 full join:

select coalesce(ae.col1, mh.col1) as col1, ae.col2, mh.col2
from (select ae.*, row_number() over (partition by col1 order by col1) as seqnum
      from ae
     ) ae full join
     (select mh.*, row_number() over (partition by col1 order by col1) as seqnum
      from mh
     ) mh
     on mh.col1 = ae.col1 and mh.seqnum = ae.seqnum
order by coalesce(ae.col1, mh.col1), seqnum;

Answer 2

这是我到目前为止更新的代码，它现在给了我正确的顺序编辑刚刚在代码末尾添加了 DESC 给我结果

select coalesce(ae.subject, mh.subject) as subject, ae.aeterms, mh.mhterms
from (select ae.*, row_number() over (partition by subject order by subject) 
as seqnum
from ae) ae full join
(select mh.*, row_number() over (partition by subject order by subject) as 
seqnum from mh) mh
on mh.subject = ae.subject and mh.seqnum = ae.seqnum
order by coalesce(ae.subject, mh.subject), ae.seqnum Desc;

SQL 笛卡尔类型连接

SQL Cartesian type join

sql

join

jointable