获取关系，然后从表中获取-php＆mysql

Question

I have 3 table for example : post , attach , relation.

and when I select post, after than I need get attached file to this post.

Now I have to select from relation table. because attach can add to an other posts.

I select the post easily, then now what is the best way to select attaches?

the post table:

+----+--------------+-------------+
| id | post_title   | post_text   |
+----+--------------+-------------+
|  1 | test title 1 | test text 1 |
|  2 | test title 2 | test text 2 |
+----+--------------+-------------+

the attach table:

+----+-------------------------------+
| id | url                           |
+----+-------------------------------+
|  1 | http://xxxxxx.ir/img/logo.png |
|  2 | http://xxxxxx.ir/img/tut.png  |
+----+-------------------------------+

the relation table:

+-----+-----+
| src | dst |
+-----+-----+
|   1 |   1 |
|   1 |   2 |
+-----+-----+

and my tried sql code:

SELECT dst FROM relation where src = 1 ;

and after than I implode in php :

$ids = implode( $result );

then my final query:

SELECT * FROM attach WHERE id IN( $ids ) ;

I need better way and SQL.

Answer 1

您可以使用JOIN从附加表中引入数据。

SELECT r.src, a.* FROM relation AS r JOIN attach AS a ON r.src=a.id WHERE r.src = 1;