如何从多个mysql表中获取数据并生成一个JSON输出

I have this PHP code:

我有这个PHP代码:

 try {
      $result = $db->prepare('SELECT ID,masina,marka,model,reg_br,istek_reg,servis FROM mehanizacija WHERE user_id=:user_id');
      $result->bindParam(':user_id', $user_id); 
      $result->execute();

        foreach($result as $r) {
          $temp = array();
          $temp[] = (int) $r['ID']; 
          $temp[] = (string) $r['masina'];
          $temp[] = (string) $r['marka']; 
          $temp[] = $r['model'];
          $temp[] = (string) $r['reg_br'];
          $temp[] = 'Date('.str_replace('-',', ',($r['istek_reg'])).')';
          $temp[] = 'Date('.str_replace('-',', ',($r['servis'])).')';

        $rs = $db->prepare('SELECT sum(radnih_sati) FROM track_meh WHERE user_id=:user_id AND id_meh=:id_meh');
          $rs->bindParam(':user_id', $user_id); 
          $rs->bindParam(':id_meh', $r['ID']); 
          //$rs->bindParam(':radnici', $radnici); 
          $rs->execute();
          $sumRows = $rs->fetchColumn(); 
          $temp[] = array('v' => (int) $sumRows);
 $rs1 = $db->prepare('SELECT sum(kolicina) FROM track_meh WHERE user_id=:user_id AND id_meh=:id_meh');
          $rs1->bindParam(':user_id', $user_id); 
          $rs1->bindParam(':id_meh', $r['ID']); 
          $rs1->execute();
          $sumRows1 = $rs1->fetchColumn(); 
          $temp[] = array('v' => (int) $sumRows1);
          $prosecna = $sumRows1/$sumRows;
          $temp[] = array('v' => (float) $prosecna. ' l/h');

          $rows[] = $temp;
        }
    $table['data'] = $rows;
    $jsonTable = json_encode($table);
    } catch(PDOException $e) {
        echo 'ERROR: ' . $e->getMessage();
    }
    echo $jsonTable;
 try {