SQL：针对列的 PIVOTting 计数和百分比

Question

我正在尝试生成一份报告，显示每个零件编号的这些零件的测试结果，包括通过和失败的数量，以及通过和失败的百分比。

到目前为止，我有以下内容：

SELECT r2.PartNo, [Pass] AS Passed, [Fail] as Failed
    FROM
    (SELECT ResultID, PartNo, Result FROM Results) r1
PIVOT (Count(ResultID) FOR Result IN ([Pass], [Fail])) AS r2
ORDER By r2.PartNo

这是解决方案的一半（通过和失败的总数）；问题是，我如何推进并包括百分比？

我还没有尝试过，但我想我可以从头开始，并建立一系列子查询，但这更像是一个学习练习 - 我想知道“最好的”（最优雅或最有效）解决方案，所以我想我会寻求建议。

我可以扩展这个 PIVOT 查询，还是应该采取不同的方法？

DDL：

CREATE TABLE RESULTS (
    [ResultID] [int] NOT NULL,
    [SerialNo] [int] NOT NULL,
    [PartNo] [varchar](10) NOT NULL,
    [Result] [varchar](10) NOT NULL);

DML：

INSERT INTO Results VALUES (1, '100', 'ABC', 'Pass')
INSERT INTO Results VALUES (2, '101', 'DEF', 'Pass')
INSERT INTO Results VALUES (3, '100', 'ABC', 'Fail')
INSERT INTO Results VALUES (4, '102', 'DEF', 'Pass')
INSERT INTO Results VALUES (5, '102', 'DEF', 'Pass')
INSERT INTO Results VALUES (6, '102', 'DEF', 'Fail')
INSERT INTO Results VALUES (7, '101', 'DEF', 'Fail')

更新：

根据 bluefeet 的回答，我的解决方案是：

SELECT r2.PartNo, 
    [Pass] AS Passed, 
    [Fail] as Failed,
    ROUND(([Fail] / CAST(([Pass] + [Fail]) AS REAL)) * 100, 2) AS PercentFailed
    FROM
    (SELECT ResultID, PartNo, Result FROM Results) r1
PIVOT (Count(ResultID) FOR Result IN ([Pass], [Fail])) AS r2
ORDER By r2.PartNo

我已经舍入了一个 FLOAT（而不是 CAST 到 DECIMAL 两次），因为它的效率更高一点，而且我还决定我们只需要失败 %age。

Answer 1

听起来您只需要为 Percent Passed 和 Percent Failed 添加一列。您可以在 PIVOT 上计算这些列。

SELECT r2.PartNo
    , [Pass] AS Passed
    , [Fail] as Failed
    , ([Pass] / Cast(([Pass] + [Fail]) as decimal(5, 2))) * 100 as PercentPassed
    , ([Fail] / Cast(([Pass] + [Fail]) as decimal(5, 2))) * 100 as PercentFailed
FROM
(
    SELECT ResultID, PartNo, Result 
    FROM Results
) r1
PIVOT 
(
    Count(ResultID) 
    FOR Result IN ([Pass], [Fail])
) AS r2
ORDER By r2.PartNo