Question

我将向您展示一些表的内容。

Bolek=> SELECT id, description from "TOMBInput";
 id |    description    
----+-------------------
  1 | Virtual Input 111
  2 | Virtual Input 112
  3 | Virtual Input 113
  4 | Virtual Input 114
(4 rows)

Bolek=> SELECT id, setup_id FROM "TRBTOMBConnection";
 id | setup_id 
----+----------
  1 |        1
  2 |        1
  3 |        1
  4 |        1
(4 rows)

Bolek=> SELECT id, setname FROM "Setup";
 id |   setname   
----+-------------
  1 | SETUP_00001
(1 row)

Bolek=> SELECT id, setup_id FROM "Run";
 id | setup_id 
----+----------
  1 |        1
(1 row)

我的查询[1]是

SELECT
  "TOMBInput".id AS tombinput_id,
  "TRBTOMBConnection".id AS trbtombconnection_id,
  "Setup".id AS setup_id,
  "Run".id AS run_id
FROM "TOMBInput" 
  INNER JOIN "TRBTOMBConnection" ON "TOMBInput".id = "TRBTOMBConnection".tombinput_id
  FULL JOIN "Setup" ON "TRBTOMBConnection".id = "Setup".id
  FULL JOIN "Run" ON "Setup".id = "Run".id AND "Run".id = 1;

结果表

 tombinput_id | trbtombconnection_id | setup_id | run_id 
--------------+----------------------+----------+--------
            1 |                    1 |        1 |      1
            2 |                    2 |          |       
            3 |                    3 |          |       
            4 |                    4 |          |       
(4 rows)

问题是我希望有像

这样的表格

 tombinput_id | trbtombconnection_id | setup_id | run_id 
--------------+----------------------+----------+--------
            1 |                    1 |        1 |      1
            2 |                    2 |        1 |      1 
            3 |                    3 |        1 |      1 
            4 |                    4 |        1 |      1 
(4 rows)

因为“TRBTOMBConnection”有4行，setup_id == 1 并且“运行”有setup_id == 1.

更重要的是，现在我改变最后一行（在我的查询[1]中）

FULL JOIN "Run" ON "Setup".id = "Run".id AND "Run".id = 2;

（在“运行”表中我们没有得到id == 2）查询的结果是

 tombinput_id | trbtombconnection_id | setup_id | run_id 
--------------+----------------------+----------+--------
            1 |                    1 |        1 |       
            2 |                    2 |          |       
            3 |                    3 |          |       
            4 |                    4 |          |       
              |                      |          |      1
(5 rows)

没关系，因为我使用了FULL JOIN。

但是在这种情况下我运行查询[1]

我想有一个空的结果表，因为“运行”没有得到id == 2并且它没有任何意义来显示表，因为一切都是从Run开始的。

如何更改查询[1]？

Answer 1

您的ID令人困惑：

SELECT
  "TOMBInput".id AS tombinput_id,
  "TRBTOMBConnection".id AS trbtombconnection_id,
  "Setup".id AS setup_id,
  "Run".id AS run_id
FROM "TOMBInput" 
  INNER JOIN "TRBTOMBConnection" ON "TOMBInput".id = "TRBTOMBConnection".tombinput_id
  INNER JOIN "Setup" ON "TRBTOMBConnection".setup_id = "Setup".id
  INNER JOIN "Run" ON "Setup".id = "Run".setup_id AND "Run".id = 1;

我认为没有理由在这里进行全外连接。

如何使用FULL JOIN获取空结果表？

1 个答案: