mysql - 左连接与子选择 - 右表列不显示

Question

我正在一家音乐会主办方的网站上工作，我必须检索每次巡演演出的第一个、最后一个和最近的 future 日期。我尝试使用以下查询来执行此操作:

SELECT tour.*, min(date) AS `startdate`, max(date) AS finaldate
  FROM tour, tour_date
  LEFT JOIN (
    SELECT tour_id, min(date) AS nextdate
      FROM tour_date 
      WHERE date>=CURDATE()
      GROUP BY tour_id
  ) AS ndtable
    ON ndtable.tour_id=tour_date.tour_id
  WHERE tour.id=tour_date.tour_id
  GROUP BY tour_date.tour_id
  ORDER BY nextdate

我得到了左表结果，但“下一个日期”列没有显示。

<小时/> 编辑:我忘了提及此查询仅与将来的演出相关，因此我能够像这样重新排列它:

SELECT tour.*, MIN(td.date) AS startdate, MAX(td.date) AS lastdate, MIN(ntd.date) AS nextdate
FROM tour
JOIN tour_date AS td
  ON tour.id=td.tour_id
JOIN tour_date AS ntd
  ON tour.id=ntd.tour_id
WHERE ntd.date>CURDATE()
GROUP BY td.tour_id
ORDER BY nextdate

我认为这更加整洁和高效:)

Answer 1

SELECT tour.*, min(date) AS `startdate`, max(date) AS finaldate, ndtable.nextdate
  FROM tour, tour_date
  LEFT JOIN (
    SELECT tour_id, min(date) AS nextdate
      FROM tour_date 
      WHERE date>=CURDATE()
      GROUP BY tour_id
  ) AS ndtable
    ON ndtable.tour_id=tour_date.tour_id
  WHERE tour.id=tour_date.tour_id
  GROUP BY tour_date.tour_id, ndtable.nextdate
  ORDER BY nextdate