mysql - 加入两个表时检索所有数据并按项目计数

Question

我有两张桌子：

Table 1: contest_video

Table Rows: cv_id, uid, cid, cn_id, video_name, video_detail, video, image, cverify, date

Table 2: contest_vote

Table Rows: vid, cv_id, voter_id, date

现在我想加入这两个表，这将与计数。喜欢一个视频的总票数（vid）（视频名称）

我试过这样：

SELECT *
FROM (`contest_video`)
  LEFT JOIN `system_user`
    ON `system_user`.`id` = `contest_video`.`uid`
  LEFT JOIN `contest_vote`
    ON `contest_vote`.`cv_id` = `contest_video`.`cv_id`
WHERE `contest_video`.`cid` = '1'
ORDER BY `contest_video`.`created_date` DESC

但它只返回数据而不计算。请需要专家帮忙。

Answer 1

你可以这样做

使用 group by 和列名而不是*

SELECT
  cv_id,
  uid,
  cid,
  cn_id,
  video_name,
  video_detail,
  video,
  image,
  cverify,
  date,
  count(`contest_video`.`cv_id`) Total
FROM (`contest_video`)
  LEFT JOIN `system_user`
    ON `system_user`.`id` = `contest_video`.`uid`
  LEFT JOIN `contest_vote`
    ON `contest_vote`.`cv_id` = `contest_video`.`cv_id`
WHERE `contest_video`.`cid` = '1'
GROUP BY `contest_video`.`video_name`
ORDER BY `contest_video`.`created_date` DESC