CI: Querying two tables in the model, explode - mysql

Question

i'm thinking about this for days now and don't come to grasps (since i'm relativley new to MVC and CI). I'm not even sure whether this is an issue with MVC, MySQL or arrays.
Situation: 2 MySQL tables
Table data: id, title, list
Table values: id, name
Querying the data table results in an array like the following (excerpt):
[4] => Array
(
[id] => 3
[title] => Foo
[list] => 1,2,3,4,6,14
)
[5] => Array
(
[id] => 4
[title] => Bar
[list] => 2,6,9,12
)
The field list contains comma separated values that correspond to some IDs of the values table like
[3] => Array
(
[id] => 12
[name] => 'value12'
)
What I try to do for each row is:
take the list-values & explode it into an array
check with the result set from the values-table (via in_array() method)
return the name values of the IDs if
include it somehow into the main result set (e.g. as a 2-dimensional array):
[5] => Array (
[id] => 4
[title] => Bar
[list] => Array (
[0] => value6
[1] => value12
...
)
)
My naive approach so far was to
run a query on each of the 2 tables
compare the 2 result sets via in_array
My main problem (while trying to strictly separate model, controller and view): How can I include the name field from the values-table in the "main loop" of the data table result set?
if($q->num_rows() > 0)
{
$data[] = $q->result_array();
foreach ($q->result() as $row)
{
$data[] = $row;
}
return $data;
}
If I use the following (cumbersome) approach i naturally get a new item each time:
foreach ($q->result_array() as $row)
{
$data[]['id'] = $row['id'];
$data[]['title'] = $row['title'];
$data[]['list'] = $row['year'];
}
Since this is a MySQL database I see no way to do the explode and the comparison in SQL (with LIKE or something else).
Any hint, even a simple link to an info bit, is highly appreciated.
Thanks a trillion!
fab

Answer 1

There is a many-to-many relationship between lists and list values. The conventional way to model this in a relational database is to create a joining table. So I'd structure your schema like this.
lists : list_id, title
values : value_id, name
list_values : list_id, value_id
list_values is the joining table. It links lists with values.
To build a list you could have the following functions in your model
function build_list($list_id)
{
$list = $this->get_list($list_id);
$list->values = $this->get_list_values($list_id);
return $list;
}
function get_list($list_id)
{
$sql = 'select * from lists where list_id=?';
return $this->db->query($sql, array($list_id))->row();
}
function get_list_values($list_id)
{
$sql = 'select v.value_id, v.name
from list_values lv
join values v on v.value_id=lv.value_id
where lv.list_id=?';
return $this->db->query($sql, array($list_id))->result();
}