Question

我有这个问题，它不会给我带来任何错误。每个子查询在单独运行时按预期工作。当我运行整个事情时，如下所示，我只得到列：post_title＆amp; views

SELECT post_title, 
       views, 
       coupons_today, 
       coupons_lifetime, 
       coupons_remaining 
FROM   wp_posts p 
       LEFT JOIN wp_act ct --has views column
              ON ct . campaign_id = p . id 
       LEFT JOIN(SELECT Count(*)    AS coupons_today, 
                        campaign_id cid 
                 FROM   wp_act 
                 WHERE  date = CURRENT_DATE) AS act1 
              ON act1 . cid = p . id 
       LEFT JOIN(SELECT Count(*)    AS coupons_lifetime, 
                        campaign_id cid2 
                 FROM   wp_act) AS act2 
              ON act2 . cid2 = p . id 
       LEFT JOIN(SELECT Count(*)    AS coupons_remaining, 
                        campaign_id cid3 
                 FROM   wp_ac 
                 WHERE  status IS NULL) AS ac 
              ON p . id = ac . cid3 
WHERE  p . post_status = 'publish'
AND p . post_type = 'page'
AND p . ping_status = 'open';

Answer 1

以这种方式尝试：

SELECT  p.post_title,
        ct.views, 
      ( SELECT  Count(*)
            FROM  wp_act
            WHERE  date = CURRENT_DATE
              AND  campaign_id = p.id 
      ) AS coupons_today, 
      ( SELECT  Count(*)
            FROM  wp_act
            WHERE  campaign_id = p.id 
      ) AS coupons_lifetime, 
      ( SELECT  Count(*)
            FROM  wp_ac
            WHERE  status IS NULL
              AND  campaign_id = p.id 
      ) AS coupons_remaining
    FROM  wp_posts p
    LEFT JOIN  wp_act ct  ON ct . campaign_id = p . id
    WHERE  p . post_status = 'publish'
      AND  p . post_type = 'page'
      AND  p . ping_status = 'open';

Answer 2

在朋友的帮助下（感谢Swaroop）我最终得到了这个：

    SELECT    p.post_title,
      ct.views         AS views,
      ct.coupons       AS coupons_today,
      Sum(ctl.coupons) AS coupons_lifetime,
     (SELECT Count(*) FROM wp_ac WHERE c.campaign_id = p.id AND c.status IS NULL)
      AS coupons_remaining
    FROM wp_posts p
    LEFT JOIN wp_act ct  ON ct.campaign_id = p.id  AND ct.date = CURRENT_DATE
    LEFT JOIN wp_act ctl ON ctl.campaign_id = p.id
    WHERE p.post_status = 'publish'
      AND p.post_type = 'page'
      AND p.ping_status = 'open'
    GROUP BY p.id

如何在子查询中LEFT JOIN Count

2 个答案: