如何从codeigniter中用逗号分隔的每个id中从其他表中选择多个数据

Question

我有这样的表

tbl_post

+-----------+--------------+
| post_id   | post_content |
+-----------+--------------+
| 1         |  contentone  |
+-----------+--------------+

tbl_category

+-------------+---------------+
| category_id | category_name |
+-------------+---------------+
|           1 | Politic       |
|           2 | Social        |
|           3 | Economy       |
+-------------+---------------+

tbl_category_post

+------------------+-------------+---------+
| category_post_id | category_id | post_id |
+------------------+-------------+---------+
|                1 |           1 |       1 |
|                2 |           2 |       1 |
|                3 |           3 |       1 |
+------------------+-------------+---------+

然后我想要像这样的输出

+--------------+--------------------------+
| post_content |         category         |
+--------------+--------------------------+
|            1 | Politic, Social, Economy |
+--------------+--------------------------+

然后如何使用codeigniter显示这样的数据，我真的很困惑，有人请帮助我！

Answer 1

编辑：使用Codeigniter（未经过测试）：

$this->db->select('post_id, GROUP_CONCAT(tc.category_name) AS category_name')
->from('tbl_category_post tcp')
join->('tbl_category tc', 'tc.category_id=tcp.category_id', 'left')
->group_by('tcp.post_id');

我想你需要PHP循环方法来循环这个。

使用mysql GROUP_CONCAT函数：

SELECT post_id, GROUP_CONCAT(tc.category_name) AS category_name
FROM tbl_category_post tcp
LEFT JOIN tbl_category tc ON tc.category_id=tcp.category_id
GROUP BY tcp.post_id