Query Improvement: foreach - php

Question

I have the following model function and I was wanting to know how I could improve it and also pull the needed $row out when needed so that I dont get a PHP error.
How I am pulling the required data:
$data['companyName'] = $this->core_model->companyDetails('coreCompanyName');
Errors:
Undefined property: stdClass::$coreContactName
Undefined property: stdClass::$coreContactEmail
Model:
function companyDetails()
{
$this->db->select('coreCompanyName, coreContactName, coreContactEmail');
$this->db->from('core');
$whereData = array('coreCompanyName' => $companyName, 'coreContactName' => $companyContactName, 'coreContactEmail' => $companyContactEmail);
$this->db->where($whereData);
$query = $this->db->get();
$result = '';
if ($query->num_rows() > 0)
{
foreach ($query->result() as $row)
{
$result .= $row->coreCompanyName;
$result .= $row->coreContactName;
$result .= $row->coreContactEmail;
}
}
return $result;
}

Answer 1

It should be like this
$this->db->select('coreCompanyName, coreContactName, coreContactEmail');
not
$this->db->select('coreCompanyName','coreContactName','coreContactEmail');
See reference http://codeigniter.com/user_guide/database/active_record.html#select
To limit to a specific set of records, use the where() function. e.g.
$this->db->where('companyId', $companyId);

Answer 2

<?php
/**
*
* WHERE ARE : $companyName, $companyContactName, $companyContactEmail being defined ?
* WHY return 'companyName' WHEN You are quering based on the '$companyName' ???
* Your query wil fail with out it, that that's all your using ?
*
*/
function companyDetails() {
$query = $this->db->query("SELECT companyName FROM core WHERE coreCompanyName = ? AND coreContactName = ? AND coreContactEmail = ? LIMIT 1",
array($companyName, $companyContactName, $companyContactEmail));
return ($query->num_rows() == 1) ? $query->row()->companyName : FALSE;
}

Answer 3

Change:
$this->db->select('coreCompanyName','coreContactName','coreContactEmail');
To:
$this->db->select('coreCompanyName, coreContactName, coreContactEmail');
Now, you said this pulls all the data, but you aren't actually filtering the result. I wonder what the required data is