Question

假设我有来自多个人的多组报告。如何识别这些数据之间的更改并确定将哪些数据合并到特定数据库。

适用的情景

数据1中存在数据但数据2中存在数据时
数据2中存在数据但数据1
当两个表中的数据不匹配时（无论是销售额/收入）还是假设有更多列而不仅仅是可能具有不同值的收入

数据1

Date        Sales   Revenue
2016-01-01  27      30
2016-01-03  12      10
2016-01-04  48      50

数据2

Date        Sales   Revenue
2016-01-01  27      10
2016-01-02  31      40
2016-01-04  48      50

期望的结果

Date        Sales   T1 Revenue  T2 Revenue
2016-01-01  27      30          10
2016-01-02  31      NULL        40
2016-01-03  12      10          NULL
2016-01-04  48      50          50

我尝试了各种方法，包括UNION和JOIN的组合，现在似乎对我没什么用。

我现在最接近的是以下内容。

SELECT d1.date,
       d1.sales,
       d1.revenue AS T1,
       d2.revenue AS T2

FROM dataset1 d1

RIGHT JOIN dataset2 d2 ON d1.date = d2.date

WHERE d1.revenue <> d2.revenue
OR (d1.revenue IS NOT NULL AND d2.revenue IS NULL)
OR (d1.revenue IS NULL AND d2.revenue IS NOT NULL)

左连接/右连接之间的跳转仅取决于哪一侧有缺失数据。

搜索了该网站但未找到适用于我的解决方案= /

Answer 1

SELECT x.*
     , d1.revenue t1_revenue
     , d2.revenue t2_revenue
  FROM (SELECT date, sales FROM data1
         UNION
        SELECT date, sales FROM data2
       ) x
  LEFT
  JOIN data1 d1
    ON d1.date = x.date
  LEFT
  JOIN data2 d2
    ON d2.date = x.date
 ORDER
    BY date;

Answer 2

您应该使用full join。

SELECT coalesce(d1.date,d2.date) dt,
       coalesce(d1.sales,d2.sales) sales,
       d1.revenue AS T1Revenue,
       d2.revenue AS T2Revenue
FROM dataset1 d1
FULL JOIN dataset2 d2 ON d1.date = d2.date

当列在任一给定表中不存在时，使用coalesce获取列的非空值。

由于MySQL不支持full join，因此可以将left和right联接与union结合使用来完成此操作。

SELECT d1.date dt,
       d1.sales sales,
       d1.revenue AS T1Revenue,
       d2.revenue AS T2Revenue
FROM dataset1 d1
LEFT JOIN dataset2 d2 ON d1.date = d2.date
UNION
SELECT d2.date dt,
       d2.sales sales,
       d1.revenue AS T1Revenue,
       d2.revenue AS T2Revenue
FROM dataset1 d1
RIGHT JOIN dataset2 d2 ON d1.date = d2.date
ORDER BY 1

Answer 3

一种方法是蛮力：

select 'd1' as which, d1.*
from data1 d1
where not exists (select 1
                  from data2 d2
                  where d1.date = d2.date and d1.revenue <=> d2.revenue
                 )
union all
select 'd2' as which, d2.*
from data1 d2
where not exists (select 1
                  from data1 d1
                  where d1.date = d2.date and d1.revenue <=> d2.revenue
                 );

您的示例查询仅比较revenue，但您可以使用相同的逻辑来比较sales。请注意，<=>是NULL - 安全比较运算符。

MySQL - 使用join在两个表上获取两组数据之间的差异？

3 个答案: