FROM is adding 1 to SQL..

The first argument to get_where should be the name of the table. Fix that and see what happens.

PERS is name of the table.

Your code

PHP Code:

->get_where(array('PERS.id' => $person_id)); 


supplies only one argument. Try

PHP Code:

->get_where('PERS', array('PERS.id' => $person_id)); 


On further consideration, you could probably do this

PHP Code:

$company = $ci->db
    ->select('*')
    ->from('musteriler as MUST')
    ->join('ilgili_kisiler AS PERS', 'PERS.musteri_id = MUST.id', 'inner')
   ->where(array('PERS.id' => $person_id))
   ->get(); 


I believe that select('*') in combination with the join statment will give you all fields from both tables.