SQL 查询 GROUP BY 分组

Question

我有这样的东西：

id	name	totalAmount
1	name1	10
2	name1	20
3	name1	25
4	name2	5
5	name2	12

并且需要看起来像这样：

id's	name	totalAmount
1,2	name1	30
2,3	name1	45
1,3	name1	35
1,2,3	name1	55
4,5	name2	17

我正在使用 STRING_AGG 但不知道如何分隔前 3 个 ID。

Answer 1

-- *** Test Data ***
CREATE TABLE #t
(
    id int NOT NULL PRIMARY KEY
    ,[name] nvarchar(30) NOT NULL
    ,totalAmount money NOT NULL
);
INSERT INTO #t
VALUES (1, 'name1', 10)
,(2, 'name1', 20)
,(3, 'name1', 25)
,(4, 'name2', 5)
,(5, 'name2', 12);
-- *** End Test Data ***

SELECT CAST(T1.id AS varchar(10))
        + ',' + CAST(T2.id AS varchar(10)) AS ids
    ,T1.[name] AS [name]
    ,T1.totalAmount + T2.totalAmount AS totalAmount
FROM #t T1
    JOIN #t T2
        ON T1.[name] = T2.[name]
WHERE T1.id < T2.id

UNION ALL

SELECT CAST(T1.id AS varchar(10))
        + ',' + CAST(T2.id AS varchar(10))
        + ',' + CAST(T3.id AS varchar(10)) AS ids
    ,T1.[name] AS [name]
    ,T1.totalAmount + T2.totalAmount + T3.totalAmount AS totalAmount
FROM #t T1
    JOIN #t T2
        ON T1.[name] = T2.[name]
    JOIN #t T3
        ON T1.[name] = T3.[name]
WHERE T1.id < T2.id
    AND T2.id < T3.id;

Answer 2

这是一个递归版本，可以处理超过 3 个 id 的名称和 returns 所有可能的组合。正如 Dai 指出的那样，要小心，因为组合的数量会迅速增加。但是如果你的真实数据就像你的例子（通常每个名字有 2-3 个 ID）那么它应该没问题。

值得注意的是，我这样做是为了好玩。也许您最好只存储原始数据并在应用程序层中执行此类恶作剧。

CREATE TABLE #data
(
    id INT,
    [name] VARCHAR(10),
    totalAmount INT 
);
INSERT INTO #data
VALUES 
(1, 'name1', 10),
(2, 'name1', 20),
(3, 'name1', 25),
(4, 'name2', 5),
(5, 'name2', 12);

WITH cte (name, ids, maxid, tot) AS
(
    SELECT a.name, 
        CONVERT(VARCHAR(8000), CONVERT(VARCHAR(10), a.id) + ',' + CONVERT(VARCHAR(10), b.id) ) AS ids, 
        b.id AS maxid,
        a.totalAmount + b.totalAmount AS tot
    FROM #data a
    INNER JOIN #data b ON b.name = a.name AND a.id < b.id
    UNION ALL
    SELECT cte.name,
        CONVERT(VARCHAR(8000), cte.ids + ',' +CONVERT(VARCHAR(10), a.id)), 
        a.id AS maxid,
        cte.tot + a.totalAmount
    FROM cte
    INNER JOIN #data a ON cte.name = a.name
    WHERE a.id > cte.maxid
)
SELECT ids, name, tot
FROM cte

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