sql - 合并 SQL 数据？

Question

这看起来很简单，但我似乎不知道该怎么做。我有两个数据集:

SET1
DATE       | TOTAL1 | TOTAL2 | TOTAL3
1 Jun 2013 | 0      | 0      | 5
2 Jun 2013 | 0      | 0      | 12
3 Jun 2013 | 0      | 0      | 34
4 Jun 2013 | 0      | 0      | 50

SET2
DATE       | TOTAL1 | TOTAL2 | TOTAL3
1 Jun 2013 | 1      | 2      | 0
2 Jun 2013 | 4      | 12     | 0
3 Jun 2013 | 5      | 12     | 0
4 Jun 2013 | 6      | 10     | 0

我想创建第三个数据集，将这两个集合合并成以下内容:

SET3
DATE       | TOTAL1 | TOTAL2 | TOTAL3
1 Jun 2013 | 1      | 2      | 5
2 Jun 2013 | 4      | 12     | 12
3 Jun 2013 | 5      | 12     | 34
4 Jun 2013 | 6      | 10     | 50

加入表是行不通的。如果日期匹配，我需要以一种将合计相加的方式加入他们。知道如何做到这一点吗？

Answer 1

SELECT
     DATE,
     SUM(TOTAL1) AS TOTAL1,
     SUM(TOTAL2) AS TOTAL2,
     SUM(TOTAL3) AS TOTAL3
FROM
(
     SELECT
          DATE,
          TOTAL1,
          TOTAL2,
          TOTAL3
     FROM
         SET1

     UNION ALL

     SELECT
          DATE,
          TOTAL1,
          TOTAL2,
          TOTAL3
     FROM
         SET2
) SubQueryAlias
GROUP BY
     DATE