How to make a percentage on mysql codeigniter

Question

I have a table with 2 fields. Id_user first field and the second field type of browser, I tried to make a percentage of the total number of users favorite browser based user. after I try to make her its query results do not match a percentage of her, what's wrong?

|id_user|   name_item
--------------------------
|   1   |   safari      |
|   2   |   firefox     |
|   3   |   opera mini  |
|   4   |   safari      |
|   5   |   chrome      |   
|   6   |   firefox     |
|   7   |   chrome      |
|   8   |   chrome      |   
|   9   |   firefox     |
|   10  |   firefox     |       
|   11  |   safari      |
|   12  |   opera mini  |   

which are expected

|   safari      |   25% |
|   opera mini  |   17% |
|   firefox     |   33% |
|   chrome      |   25% |

Controllers

public get_json() {
    $browser = $this->My_model->get_browser();
    foreach($browser as $row)
    {   
        $data['browser'] []= $row['browser'];
        $data['percentage'] []= $row['data_percentage'];
    }       
        header('content-type: application/json');   
        echo json_encode($data);  
}   

Models

function get_browser() {
    $query = $this->db->select('browser, 100 / count(*) as data_percentage')
                      ->from('tb_browser')
                      ->group_by('browser')
                      ->get();      
    return $query->result_array();  
}   

Answer 1

You should be dividing COUNT(*) for each group by the total number of records in the table. For the latter quantity, you can use the following subquery:

SELECT COUNT(*) FROM tb_browser

Here is the full code:

function detail_metagenome_microbe_grafik($trflp_code, $metacode) {
    $total = '(select count(*) from tb_browser)';
    $query = $this->db->select('concat(round((100*count(*))/'.$total.',0),"%") as data_percentage')
                  ->from('tb_browser')
                  ->group_by('browser')
                  ->get();      
    return $query->result_array();  
}

Answer 2

Try this,

$query = $this->db->select('browser, (count(*) / <total_rec_count>) *100 as data_percentage')
                  ->from('tb_browser')
                  ->group_by('browser')
                  ->get();      
return $query->result_array(); 

Answer 3

need to get the actual total to do the calculation

$query = $this->db->select('browser, (count(*) / (select count(*) from tb_browser)) *100 as data_percentage')

I'm a bit rusty at mysql and haven't got an instance handy... unfortunately mysql doesn't support OVER()