明确的双向关系

Question

我有一个表来描述数据库中其他表之间的关系。每个用户都可以拥有任何文件，每个文件都可以拥有任何用户。

如果我得到一个文件的关系并且我没有这个文件与用户的关系，但用户与那个文件有关系。我想看看。

当两者都与自己有关系时，我不想看到两次记录。

作为输入，我有记录类型和记录 ID。如何实现？

闭表：

+--------------------+--------------+------+-----+---------+----------------+
| Field              | Type         | Null | Key | Default | Extra          |
+--------------------+--------------+------+-----+---------+----------------+
| id                 | int(11)      | NO   | PRI | NULL    | auto_increment |
| record_id          | int(11)      | NO   |     | NULL    |                |
| record_type        | varchar(200) | NO   |     | NULL    |                |
| second_record_id   | int(11)      | NO   |     | NULL    |                |
| second_record_type | varchar(200) | NO   |     | NULL    |                |
+--------------------+--------------+------+-----+---------+----------------+

样本数据：

+----+-----------+-------------+------------------+--------------------+
| id | record_id | record_type | second_record_id | second_record_type |
+----+-----------+-------------+------------------+--------------------+
|  1 |         1 | files       |                1 | users              |
|  2 |         2 | users       |                1 | files              |
|  3 |         3 | users       |                1 | files              |
|  4 |         2 | files       |                1 | users              |
|  5 |         1 | users       |                1 | files              |
|  6 |         1 | files       |                3 | users              |
+----+-----------+-------------+------------------+--------------------+

我试过了

SELECT * FROM closure 
WHERE record_id=1 OR second_record_id = 1 
AND record_type="files" OR second_record_type="files" 
GROUP BY "files" 
HAVING record_id=1 OR second_record_id=1

但它让我有了一个关系：

+----+-----------+-------------+------------------+--------------------+
| id | record_id | record_type | second_record_id | second_record_type |
+----+-----------+-------------+------------------+--------------------+
|  1 |         1 | files       |                1 | users              |
+----+-----------+-------------+------------------+--------------------+

我想要的结果是：

+----+-----------+-------------+------------------+--------------------+
| id | record_id | record_type | second_record_id | second_record_type |
+----+-----------+-------------+------------------+--------------------+
|  1 |         1 | files       |                1 | users              |
|  2 |         2 | users       |                1 | files              |
|  6 |         1 | files       |                3 | users              |
+----+-----------+-------------+------------------+--------------------+

Sql fiddle

---

编辑

我终于删除了 id 列。

Answer 1

我认为您只想针对每种记录类型比较同一类型的“1”和“文件”。这应该会产生您想要的结果：

SELECT c.*
FROM closure c
WHERE (record_id = 1 and record_type = 'files') OR
      (second_record_id = 1 and second_record_type = 'files');

Answer 2

您没有聚合功能，因此如果您不想 distinct add distinct 子句（但使用 id 不允许正常工作）， group by 和 having 子句是无用的

SELECT  * 
FROM closure 
WHERE ( record_id=1 OR second_record_id = 1 ) 
AND  (record_type="files" OR second_record_type="files" )

或

SELECT distinct record_id, record_type, second_record_id, second_record_type 
FROM closure 
WHERE ( record_id=1 OR second_record_id = 1 )
AND ( record_type="files" OR second_record_type="files" )