Codeigniter SQL查询返回单个值

Question

I am working with CodeIgniter and I want to get the highest ID out of a table. This i realize with a function in the Model. But I don't get the result, which is a single value, as value back.

Code:

 function get_highest_answer_id(){
   $this->db->query('SELECT MAX(id) AS answerid FROM pa_it_answer;');
    if ($query = $this->db->get()) {
        if ($query->num_rows() > 0) {
            return $query->result();
        } else {
            return array();
        }
    } else {
        return FALSE;
    }
}

How do I have to Change the code that when I call this function in my Controller I get the single value?

Answer 1

Below code is works fine for me.

$MAXID = 0;
$row = $this->db->query('SELECT MAX(id) AS answerid FROM pa_it_answer')->row();
if ($row) {
    $MAXID = $row->answerid; 
}

Answer 2

Try this:

function get_highest_answer_id(){
   $this->db->query('SELECT MAX(id) AS answerid FROM pa_it_answer;');
    if ($query = $this->db->get()) {
        if ($query->num_rows() > 0) {
            return $query->row(); // here!!!
        } else {
            return array();
        }
    } else {
        return FALSE;
    }
}

I recommended use the querybuilder of CI (EDITED)

$this->db->select_max('id', 'answerid');
$query = $this->db->get('pa_it_answer');

var_dump( $query );
var_dump( $query->answerid );
die();

Answer 3

Change your query in codeigniter like this

function get_highest_answer_id(){
     $this->db->select('MAX(id) AS answerid');
        if ($query = $this->db->get('pa_it_answer')) {
            if ($query->num_rows() > 0) {
                return $query->result();
            } else {
                return array();
            }
        } else {
            return FALSE;
        }
    }

Answer 4

You just have to simplify your method with row()

function get_highest_answer_id(){
        $record = $this->db->query('SELECT MAX(id) AS answerid FROM pa_it_answer;')->row();
        if ($record) {
            return $record->answerid;
        } 
        else {
            return FALSE;
        }
    }