public function initQuery()
    {
        if (!$this->table) {
            throw $this->exception('$table property must be defined');
        }
        $this->dsql = $this->db->dsql();
        $this->dsql->debug($this->debug);
        $this->dsql->table($this->table, $this->table_alias);
        $this->dsql->default_field = $this->dsql->expr('*,'.
            $this->dsql->bt($this->table_alias ?: $this->table).'.'.
            $this->dsql->bt($this->id_field))
            ;
        $this->dsql->id_field = $this->id_field;

        return $this;
    }