SQL笛卡尔类型联接 [英] SQL Cartesian type join

问题描述

我有2个表(此示例已简化)，我想以特定的方式进行联接.

I have 2 tables (simplified for this example) which I want to join in a particular way.

• 表1(ae)具有主题编号，ae术语
• 表2(mh)具有主题编号，mh术语

这里有帮助的构架

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:

I want my output to look like this:

有什么帮助吗?如您所见，它是我所需要的粗糙的加入！

Any help out there? As you can see its a gnarly join I need!

推荐答案

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;

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