php - add two different query in codeigniter -

i want add 2 query not working. here's my

model page:

 public function updatetable(){   $first=  $this->db->query("select column1 table table_id='data1' ,      field_id=6"); // data type numeric. when query this, result 0.0   $second=  $this->db->query("select column1 table table_id='data2' ,      field_id=6"); // data type numeric also. when query this, result 0.0   $total=$first+$second;   } 

when try run got error message

message: object of class ci_db_postgre_result not converted int 

how can make happen or possible?

edit: new info

i want use $total if statement .

 if ($total==0){  //code here  } 

what should do?

let's see first example in ci userguide: http://ellislab.com/codeigniter/user-guide/database/results.html

$query = $this->db->query("your query");  foreach ($query->result() $row) {   echo $row->title;   echo $row->name;   echo $row->body; } 

we learn 2 things:

1. $this->db->query("your query") not return result, $query->result() does.
2. the result array of object. object names column name.

if you're sure every query return 1 result. can change code this:

$first=  $this->db->query("select column1 table table_id='data1' ,  field_id=6")->result()[0]->column1;   $second=  $this->db->query("select column1 table table_id='data2' ,  field_id=6")->result()[0]->column1; 

===== answer been revised below =====

the analysis correct code above throws error, because php regard result()[0] whole.

you can either separate them

$row = $this->db->query("select column1 table table_id='data1' ,  field_id=6")->result(); $first = $row[0]->column1; 

or use current function

  $first=  current($this->db->query("select column1 table table_id='data1' ,  field_id=6")->result())->column1;