code: public function exec()
      {
        // If there's a custom query to execute, do that instead of building one.
        if ($this->customQuery) {
          return $this->execCustom();
        }
        
        // Save copy of relevant data so we can calculate the total rows of this query
        // Does not save LIMIT as this is for use with pagination.
        $this->last_wheres = $this->wheres;
        $this->last_distinct = $this->distinct;
        $this->last_ins = $this->ins;
        $this->last_groupBys = $this->groupBys;
        $this->last_havings = $this->havings;
        $this->last_joins = $this->joins;
        
        // Execute this query
        $this->calculate();
        try {
            $result = $this->db->query($this->query);
        }
        catch (\PDOException $e) {
            if ($this->config['mode'] == 'development') {
                echo $this->getQuery();
            }
            $this->reset();
            throw $e;
        }
        $this->reset();
        
        // Return Result
        $dbResult = new Db_MySQLResult($result, $this->db);
        return $dbResult;
      }
docs: Create SQL string and execute it on our database.