SQL按CASE WHEN聚合记录。

Question

我正试图根据符合以下条件的值来汇总记录的总和。CASE WHEN 我可以汇总总和，但我不知道如何根据记录的 description 值。

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

我的查询结果如下

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

然而，我真正想实现的是，如果记录有相同的 Description 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，它应该将这2行合并，并添加18000 + 500 = 18500。DueDate和Age列只是作为参考。最重要的字段是 TotalAmount 和 Description

我试着用别名 Description 属于 CASE-WHEN 但我没有工作。

我希望得到任何帮助。

谢谢

Answer 1

你复制并粘贴 CASE 语句进入 GROUP BY 子句。

GROUP BY T1.Company, CASE WHEN ...

这有很多代码要重复。

或者你可以使用通用表表达式（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