mySQL查詢連接五個表

Question

我有以下五個表（為簡潔起見省略了一些字段）

(campaign)
campaign_id
===========
campaign_name
campaign_description


(ad_group)
campaign_id
===========
group_id
===========
group_name


(used_ad)
campaign_id
===========
group_id
===========
ad_id
===========


(billboard_group)
campaign_id
===========
group_id
===========
group_name


(used_billboard)
campaign_id
==============
group_id
==============
billboard_code
==============

因此，“廣告系列”由1）“ad_group”和2）“billboard_group”組成。 ad_group包含許多廣告（存儲在“used_ad”組中），而billboard_group包含許多廣告牌（存儲在“used_billboard”組中）。

我想運行一個返回所有廣告系列的查詢，並列出與該廣告系列相關的廣告和廣告牌總數。 我只能為ad_group執行此操作，但不能執行ad_group AND billboard_group。

例如，這個查詢：

SELECT campaign.*, COUNT(used_ad.ad_id) AS used_ads
FROM campaign
LEFT JOIN ad_group 
  ON campaign.campaign_id = ad_group.campaign_id
LEFT JOIN used_ad
  ON ad_group.group_id = used_ad.group_id
  AND used_ad.campaign_id = campaign.campaign_id
GROUP BY campaign.campaign_id

給出這樣的列表：

campaign_id     campaign_name     campaign_description    used_ads
1               Test campaign     Testing                 4
2               Second campaign   Second                  0

但我所追求的是：

campaign_id     campaign_name     campaign_description    used_ads    used_billboards
1               Test campaign     Testing                 4           5
2               Second campaign   Second                  0           3

只有我似乎無法弄清楚如何從BOTH used_ad和used_billboard中包含計數。 我會感激任何幫助。

Answer 1

為了避免笛卡爾乘法，我將分別對used_ad和used_billboard分組和計數，然后才加入它們：

SELECT campaign.*, ag.used_ads_count, bg.used_billboards_count
FROM campaign c
LEFT JOIN  (SELECT    campaign_id, COUNT(*) AS used_ads_count
            FROM      ad_group ag
            LEFT JOIN used_ad ua ON ag.group_id = ua.group_id
            GROUP BY  campaign_id) ac ON c.campaign_id = ac.campaign_id
LEFT JOIN  (SELECT    campaign_id, COUNT(*) AS used_billboards_count
            FROM      billboard_group bg
            LEFT JOIN used_billboard ub ON bg.group_id = ub.group_id
            GROUP BY  campaign_id) bc ON c.campaign_id = bc.campaign_id

Answer 2

如果billboard_code是唯一的，這樣的東西可能會有效：

SELECT
  c.campaign_id, c.campaign_name, 
  COUNT(DISTINCT u.ad_id) AS used_ads,
  COUNT(DISTINCT b.billboard_code) AS used_billboards
FROM
campaign c
LEFT JOIN ad_group a ON c.campaign_id = a.campaign_id
LEFT JOIN used_ad u ON a.group_id = u.group_id
  AND c.campaign_id = u.campaign_id
LEFT JOIN used_billboard b ON c.campaign_id = b.campaign_id
  AND b.group_id = a.group_id
GROUP BY c.campaign_id

Answer 3

SELECT campaign.*, COUNT(used_ad.ad_id) AS used_ads, COUNT(used_billboard.billboard_code) as used_billboards
FROM campaign
LEFT JOIN ad_group 
  ON campaign.campaign_id = ad_group.campaign_id
LEFT JOIN billboard_group
  ON campaign.campaign_id = billboard_group.campaign_id
LEFT JOIN used_ad
  ON ad_group.group_id = used_ad.group_id
  AND used_ad.campaign_id = campaign.campaign_id
LEFT JOIN used_billboard
  ON billboard_group.group_id = used_billboard.group_id
  AND used_billboard.campaign_id = campaign.campaign_id
GROUP BY campaign.campaign_id