3张桌子之间的杂货杂货集关系

Question

I have 3 sql tables and they are with this form.

TEST

• test_id
• test_name

EXAMPLE

• example_id
• example_test_id

SOMETHING

• something_id
• something_example_id

So i want to take the name of the TEST table among with the id and send it to the table EXAMPLE, and then the example_id should be sent to SOMETHING table. Finishing the relation i want the name of the TEST table to be shown by the example_id in the SOMETHING table.

We have tried this

 $crud->set_relation_n_n('something','example','test','example_id','example_test_id','test_name');

And it takes the id of the TEST and it saves it to example_test_id but we want it to be saved at something_example_id and show the test_name. All the tables have foreign keys and primary keys. Hope you understand.

Answer 1

It would be easier for you if you were using custom model functions instead of set_relation_n_n function.

First create a model function to get all the id and test_id from example table

public function get_example_list()
    {
        $this->db->select('example_id, example_test_id');
        $this->db->order_by('example_id asc');
        return $this->db->get('example')->result();
    }

Next, create a second model function to get tha test_name using the test_id from the first model

public function get_test_names($id)
    {
        $this->db->select('test_name');
        $this->db->from('test');
        $this->db->where('test_id', $id);
        $name=$this->db->get();
        return $name->row()->test_name; 
    }

in your controller use the above functions to create an array with the data you need

$list = $this->your_model->get_example_list();

        foreach ($list as $column => $data) {
            $myarray[$data->example_id] = $this->your_model->get_test_names($data->example_test_id);
        }

finally use "field_type" function to pass the array into something_example_id.

$crud->field_type('something_example_id','dropdown',$myarray);

Now. in something_example_id column you have a dropdown, displaying the test_name value and saving the example_id value on your database.

Answer 2

If you don't need separate drop-downs, you can create DB view on example table:

create view_example as
  select example.*, test.test_name as test_name
  from example left outer join test on 
    example.example_test_id = test.test_id

and then in your controller for table something_example_id:

$crud->set_primary_key('example_id','view_example');
$crud->set_relation('something_example_id', 'view_example', '{test_name}.{example_id}');