获取所有项目按特定列值分组

Question

I have a table as below in MYSQL:

cname | vname | curl
---------------------
A     | 1     | url1
A     | 2     | url2
B     | 1     | url3
B     | 3     | url4
C     | 2     | url5
C     | 3     | url5
C     | 4     | url6
D     | 2     | url7

And I want to show the result as under:

1  |  2  |  3  |  4
-------------------
A  |  A  |  B  |  C
B  |  C  |  C  |
   |  D  |  

In short, I am trying to show all the cnames group by vnames.

I have tried the following code in Codeigniter:

$this->db->distinct();
$this->db->select('vname, cname, curl');
$this->db->from('tablename');
$this->db->order_by('cname');
$this->db->group_by('vname');
$res = $this->db->get();
if($res->num_rows()>0)
    var_dump($res->result());

I am getting only one row per vname as a result of var_dump();

Plesae provide a solution for this problem.

Answer 1

Use GROUP_CONCAT

$this->db->select('vname,GROUP_CONCAT(cname SEPARATOR ",") as cname');
$this->db->from('tablename');
$this->db->group_by('vname');
$res = $this->db->get();

Output :

+--------+--------+
| vname  | cname  |
+--------+--------+
| 1      | A,B    |
| 2      | A,C,D  |
| 3      | B,C    |
| 4      | C      |
+--------+--------+