我有一个SQL语句的野兽，我希望得到一些帮助。我发现我需要对其中一些表使用OUTER连接，但是MySQL没有这个功能。
SELECT validclick.CampaignName AS CampaignName,
validclick.Website AS Website,
validclick.RevClicks AS RevClicks,
validclick.Revenue AS Revenue,
validclick.TQ AS TQ,
validclick.Source AS Source,
validclick.ScoredClicks AS ScoredClicks,
validclick.Searches AS Searches,
vci.Impressions AS Impressions,
(validclick.RevClicks / validclick.Searches * 100) AS CTR,
(IFNULL(yaho.Spend, 0) + IFNULL(facebook.Spend, 0) + IFNULL(google.Spend, 0)) AS Spend,
(IFNULL(yaho.PaidClicks, 0) + IFNULL(facebook.PaidClicks, 0) + IFNULL(google.PaidClicks, 0)) AS PaidClicks,
(validclick.Revenue -
(IFNULL(yaho.Spend, 0) + IFNULL(facebook.Spend, 0) + IFNULL(google.Spend, 0))) AS Profit,
(validclick.TQ / validclick.ScoredClicks) AS ScoredTQ,
(validclick.TQ / validclick.RevClicks) AS UnscoredTQ,
(validclick.Revenue /
(IFNULL(yaho.PaidClicks, 0) + IFNULL(facebook.PaidClicks, 0) + IFNULL(google.PaidClicks, 0))) AS RPI,
(validclick.Revenue / validclick.RevClicks) AS RPC,
((IFNULL(yaho.Spend, 0) + IFNULL(facebook.Spend, 0) + IFNULL(google.Spend, 0)) /
(IFNULL(yaho.PaidClicks, 0) + IFNULL(facebook.PaidClicks, 0) + IFNULL(google.PaidClicks, 0))) AS CPC,
((validclick.Revenue -
(IFNULL(yaho.Spend, 0) + IFNULL(facebook.Spend, 0) + IFNULL(google.Spend, 0))) /
(IFNULL(yaho.Spend, 0) + IFNULL(facebook.Spend, 0) + IFNULL(google.Spend, 0)) * 100) AS ROI,
(validclick.RevClicks /
(IFNULL(yaho.PaidClicks, 0) + IFNULL(facebook.PaidClicks, 0) + IFNULL(google.PaidClicks, 0)) * 100) AS Conversion
FROM
(SELECT camp.CampaignName AS CampaignName,
MAX(camp.Website) AS Website,
MAX(camp.Source) AS Source,
SUM(vc.Clicks) AS RevClicks,
SUM(vc.Revenue) AS Revenue,
SUM(vc.TQ) AS TQ,
SUM(vc.ScoredClicks) AS ScoredClicks,
SUM(vc.BiddedSearches) AS Searches
FROM
(SELECT AffID,
MAX(CampaignName) AS CampaignName,
Website,
MAX(Source) AS Source
FROM campaigns
GROUP BY AffID) AS camp
JOIN
(SELECT AffID,
SUM(Clicks) AS Clicks,
SUM(AffiliateRevenue) AS Revenue,
SUM(BiddedSearches) AS BiddedSearches,
SUM(CASE WHEN TQ > 0 THEN (TQ * Clicks) ELSE NULL END) AS TQ,
SUM(CASE WHEN TQ > 0 THEN Clicks ELSE NULL END) AS ScoredClicks
FROM validclickvc
WHERE Date BETWEEN '2018-05-06' AND '2018-05-07'
GROUP BY AffID) AS vc
ON vc.AffID = camp.AffID
GROUP BY camp.CampaignName) AS validclick
LEFT JOIN
(SELECT CampaignName,
SUM(Spend) AS Spend,
SUM(OutboundClicks) AS PaidClicks
FROM facebookads
WHERE Date BETWEEN '2018-05-06' AND '2018-05-07'
GROUP BY CampaignName) AS facebook
ON validclick.CampaignName = facebook.CampaignName
LEFT JOIN
(SELECT CampaignName,
SUM(Spend) AS Spend,
SUM(Clicks) AS PaidClicks
FROM yahoo
WHERE Date BETWEEN '2018-05-06' AND '2018-05-07'
GROUP BY CampaignName) AS yaho
ON validclick.CampaignName = yaho.CampaignName
LEFT JOIN
(SELECT CampaignName,
SUM(Cost) AS Spend,
SUM(Clicks) AS PaidClicks
FROM adwords
WHERE Date BETWEEN '2018-05-06' AND '2018-05-07'
GROUP BY CampaignName) AS google
ON validclick.CampaignName = google.CampaignName
LEFT JOIN
(SELECT camp.CampaignName AS CampaignName,
SUM(vc.Impressions) AS Impressions
FROM
(SELECT AffID,
MAX(CampaignName) AS CampaignName
FROM campaigns
GROUP BY AffID) AS camp
JOIN
(SELECT ty AS AffID,
COUNT(DISTINCT(id)) AS Impressions
FROM validclickimpressions
WHERE ts BETWEEN '2018-05-06 00:00' AND '2018-05-07 23:59'
GROUP BY AffID) AS vc
ON vc.AffID = camp.AffID
GROUP BY camp.CampaignName) AS vci
ON validclick.CampaignName = vci.CampaignName
ORDER BY CampaignName;
我知道这可能不是最有效的MySQL声明，但我们很快就会改变事物的结构，所以我没什么大不了的。现在我需要一些方法来使用OUTER join，或者使用别名来执行LEFT JOIN UNTION RIGHT JOIN。我需要完全加入的表（别名）是vci，facebook，google和yaho。关于如何解决这个问题的任何想法？
答案 0 :(得分：1)
MySQL不支持FULL [OUTER] JOIN。
我们可以使用两个单独的选择模拟MySQL中的完整外连接，并将结果组合在一起。外连接和反连接的模式。
-- outer join (all rows from a along with matching rows from b)
SELECT ... FROM a LEFT JOIN b ON ...
UNION ALL
-- anti-join (rows from b with no matching row in a)
SELECT ... FROM b LEFT JOIN a ON ... WHERE a.notnull_col IS NULL
作为一个简单的演示，有两个表a和b：
table a table b
an bn
------- -------
1 2
2 3
3 5
4 7
示例查询
-- left outer join (rows in a with matching rows from b)
SELECT a.an, b.bn
FROM a
LEFT
JOIN b
ON b.bn = a.an
UNION ALL
-- anti-join (rows from b with no match in a)
SELECT a.an, b.bn
FROM b
LEFT
JOIN a
ON a.an = b.bn
WHERE a.an IS NULL
应该返回这样的东西（没有ORDER BY子句，行的顺序是不确定的）
an bn
------- -------
1 (NULL)
2 2
3 3
4 (NULL)
(NULL) 5
(NULL) 7