Sum column values in SELECT query with Codeigniter's ActiveRecord [duplicate]

Question

Trying to get the sum of the values entered within a column (af_am_msm) from my table (non_clinical_total_tests). I want to display that total within an html table.

My error message is:

A PHP Error was encountered - Severity: Notice - Message: Array to string conversion

My MODEL:

public function af_am_sum()
{
    $this->db->select_sum('af_am_msm');
    $query = $this->db->get('non_clinical_total_tests');
    return $query->result();
}

My CONTROLLER:

public function index()
{
    $data['af_am_total'] = $this->Page_model->af_am_sum();

    $data['pages'] = $this->Page_model->get_list();
    
    $this->template->load('admin', 'default', 'district1', $data);
}

My VIEW:

<td><?php echo $af_am_total; ?></td>

Could please var_dump($af_am_total); And provide here?

Dmitry Leiko
– Dmitry Leiko

2019-12-06 12:53:51 +00:00
Commented Dec 6, 2019 at 12:53 — Dmitry Leiko
– Dmitry Leiko, Commented Dec 6, 2019 at 12:53

Vickel · Accepted Answer · 2019-12-06 16:39:01Z

2

Codeigniter's result() function always returns an array of objects. In your view you echo it out as a string, hence the error. In order to avoid that you either produce result rows, looping through the array, or:

like in your example, as you are expecting only one row (the sum of a column) you have the possibility to get this result row (without the need to loop through it) with row()->the_name_of_your_column. To simplify the output we can create an alias for the mysql sum, naming it as second parameter:

$this->db->select_sum('af_am_msm','my_sum');
$query = $this->db->get('non_clinical_total_tests');
return $query->row()->my_sum;

which echos in your view as pretended

edited Dec 6, 2019 at 16:39

answered Dec 6, 2019 at 12:49

Vickel

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4 Comments

Roberto Raymon Over a year ago

Ok, and so this will also change my variable within my Controller, and View files from $af_am_total to $my_sum correct? (I'm a super codeigniter noob)

Vickel Over a year ago

no, nothing else changes, its just a way to get the row value of the sum easier, in the line return $query->row()->my_sum; the variable $af_am_total will not change, as you continue to use in your controller $data['af_am_total'] = $this->Page_model->af_am_sum();, see also codeigniter.com/user_guide/general/…, that explains how to get dynamic data into the view

Roberto Raymon Over a year ago

Gotcha! Next I will research subtracting the sum of one column from another column, and dividing the sum of one column by the sum of another column!

U13-Forward Over a year ago

@Vickel Here is our new room chat.stackexchange.com/rooms/101945/…

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