SQL 按 CASE WHEN 聚合记录

Question

当我能够汇总总和但我不知道如何根据description值对记录进行分组时，我正在尝试根据与CASE WHEN匹配的值来汇总记录的总和。

SQL 查询：

SELECT
T1.Company, T1.DueDate, 
SUM(T1.Amount) AS TotalAmount,

DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) AS Age,
CASE
      WHEN
         DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 0 
      THEN
         'Current'
      WHEN
         DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) > 0 
         AND DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 30 
      THEN
        'Late'
END AS Description

FROM
    Table1 T1 
    LEFT JOIN
      Table2 T2 
      ON T1.Company = T2.Company 
      AND T1.YR = T2.YR 

    INNER JOIN
      Table3 T3 
      ON T1.Company = T3.Company 
      AND T3.YR = YEAR(CURRENT_DATE)

GROUP BY T1.Company,T1.DueDate, T3.FromDate

我的查询返回以下内容。

 Company    | DueDate        | TotalAmount | Age  | Description
------------+----------------+-------------+------+------------
 123        | 20200423       |    150      |   7  |   Late
 123        | 20200604       |    18000    |  -35 |   Current
 123        | 20200515       |    500      |  -15 |   Current

但是，我真正想要完成的是聚合记录，如果它们具有相同的Description值。 所以，正确的结果应该是：

  Company   | TotalAmount  |Description |
------------+--------------+------------+
 123        |     150      |  Late
 123        |     18500    |  Current

第 2 行和第 3 行属于“当前”。 因此，它应该合并 2 行并添加 18000 + 500 = 18500。DueDate 和 Age 列仅供参考。 最重要的字段是TotalAmount和Description

我尝试按CASE-WHEN中使用的别名Description进行分组，但我没有工作。

我会很感激任何帮助。

谢谢！

Answer 1

您将CASE语句复制并粘贴到GROUP BY子句中：

GROUP BY T1.Company, CASE WHEN ...

这是很多重复的代码。

或者您可以使用公用表表达式 (CTE)：

;WITH
    cte AS 
    (
        SELECT
        T1.Company, T1.DueDate, T1.Amount

        DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) AS Age,
        CASE
            WHEN
                DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 0 
            THEN
                'Current'
            WHEN
                DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) > 0 
                AND DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 30 
            THEN
                'Late'
        END AS Description

        FROM
            Table1 T1 
            LEFT JOIN
            Table2 T2 
            ON T1.Company = T2.Company 
            AND T1.YR = T2.YR 

            INNER JOIN
            Table3 T3 
            ON T1.Company = T3.Company 
            AND T3.YR = YEAR(CURRENT_DATE)
    )

SELECT      Company, Description, SUM(Amount) AS TotalAmount
FROM        cte
GROUP BY    Company, Description