Question

我有2个相同的表（_impressionsdaily，_impressionsalltime），在每天结束时，我将所有数据从每天移动到所有时间。结构是：ID，购买ID，印象，唯一，日期。

我运行以下查询：

SELECT  
    daily.purchaseID,
    SUM(daily.impression + IFNULL(alltime.impression, 0)) AS impression,
    SUM(daily.unique + IFNULL(alltime.unique, 0)) AS `unique`
    FROM _impressionsdaily daily
    LEFT JOIN _impressionsalltime alltime ON alltime.purchaseID= daily.purchaseID
    GROUP BY daily.purchaseID;

问题是，如果所有时间表中的购买都没有在日常生活中找到，我将不会看到它们。

基本上，我们的想法是每天和所有时间的所有印象总和。

--- EDIT 事情发生在每天凌晨12:00，每日表被复制到alltime然后被删除。所以给出的解决方案是错误的..

感谢您的帮助，丹尼

Answer 1

我认为你正在寻找一个Union Select。尝试这样的事情：

SELECT DISTINCT(p.ID), p.purchaseID
FROM (SELECT *
      FROM _impressionsdaily
      UNION SELECT *
      FROM _impressionsalltime) AS p
GROUP BY p.purchaseID

Answer 2

SELECT  
daily.purchaseID,
SUM(daily.impression + IFNULL(alltime.impression, 0)) AS impression,
SUM(daily.unique + IFNULL(alltime.unique, 0)) AS `unique`
FROM _impressionsdaily daily
LEFT JOIN _impressionsalltime alltime ON alltime.purchaseID= daily.purchaseID
GROUP BY daily.purchaseID;

在这种情况下，您尚未选择任何字段形式_impressionsalltime表。

您可以使用此sql从_impressionsalltime表中选择字段

SELECT  
alltime.*,
daily.purchaseID,
SUM(daily.impression + IFNULL(alltime.impression, 0)) AS impression,
SUM(daily.unique + IFNULL(alltime.unique, 0)) AS `unique`
FROM _impressionsdaily daily
LEFT JOIN _impressionsalltime alltime ON alltime.purchaseID= daily.purchaseID
GROUP BY daily.purchaseID;

mysql left join doesnt从连接表中返回行

2 个答案: