sql - SUM()、GROUP BY 和 WHERE

Question

我有一个这样的表:

Title   | Version   | Condition | Count
-----------------------------------------------
Title1  | 1.0       | 1         | 10
Title1  | 1.1       | 2         | 5
Title1  | 1.1       | 2         | 10
Title1  | 1.1       | 1         | 10
Title2  | 1.0       | 2         | 10
Title2  | 1.5       | 1         | 5
Title2  | 1.5       | 2         | 5
Title3  | 1.5       | 2         | 10
Title3  | 1.5       | 1         | 10

我想对具有 MAX()“版本”和“条件”= 2 的每一行的“计数”值求和。我希望这是结果数据集:

Title   | Version   | Condition | Count
-----------------------------------------------
Title1  | 1.1       | 2         | 15
Title2  | 1.5       | 2         | 5
Title3  | 1.5       | 2         | 10

我可以通过以下方式获取“标题”和 MAX(“版本”) 的列表，其中“条件”= 2:

SELECT DISTINCT Title, MAX(Version) AS MaxVer FROM TABLE
WHERE Condition = 2
GROUP BY Title

我不确定如何添加所有“计数”。

Answer 1

试试这个:

SELECT t1.Title, t1.Version, t1.Condition, SUM([Count]) AS Count
FROM mytable AS t1
JOIN (
  SELECT Title, MAX(Version) AS max_version
  FROM mytable
  WHERE Condition = 2
  GROUP BY Title
) AS t2 ON t1.Title = t2.Title AND t1.Version = t2.max_version
WHERE t1.Condition = 2
GROUP BY t1.Title, t1.Version, t1.Condition

Demo here