您可以使用此查询来解决您的问题：

$this->db->select('t1.product_name,t1.location, CONCAT(t2_1.first_name, " ", t2_1.last_name) AS added_by, CONCAT(t2_2.first_name, " ", t2_2.last_name) AS updated_by'); 
$this->db->from('Table 1 t1');
$this->db->join('Table 2 t2_1', 't2_1.id = t1.added_by', 'left'); 
$this->db->join('Table 2 t2_2', 't2_2.id = t1.updated_by', 'left'); 
$query = $this->db->get();
return $query->result();

您可以根据查询表1和表2内的表名进行更改

这个应该可以

$this->db->select('*')
  ->from('Table 1')
  ->join('Table 2', 'Table 2.id = Table 1.added_by', 'left')
  ->join('Table 2', 'Table 2.id = Table 1.updated_by', 'left');

$query = $this->db->get();

return $query->result();

如果有用就告诉我。

您可以使用此查询与多个列联接

$this->db->select('*')
->from('table_1')

->join('table_2', 'table_2.id = table_1.added_by AND table_2.id = table_1.updated_by', 'left');

$query = $this->db->get();

return $query->result();