Question

我正在制作音乐会发起人的网站，我必须在每次巡演中检索演出的第一个，最后一个和最近的未来日期。我试图使用以下查询执行此操作：

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

我正在获得左表结果，但是＆＃34; nextdate＆＃34;列未显示。

<小时/> 编辑：我忘了提到这个查询仅适用于将来有节目的游览，所以我能够像这样重新排列：

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

我觉得它更整洁有效：）

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

左连接子选择 - 右表列未显示

1 个答案: