对 SQL 中多列中的行计数求和的查询答案

【问题标题】：a query that sum the count of a row from multiple columns in SQL对 SQL 中多列中的行计数求和的查询
【发布时间】：2021-01-05 12:09:18
【问题描述】：

我必须编写一个查询，对多列中的行计数求和

我的代码是这样的，但是总不行：

WITH 
NextPreviousItemAndTotal
AS
(
    SELECT LAG(Datetype, 1) OVER (PARTITION BY Fname ORDER BY Datetype ASC) AS PreviousItemDate,
            LAG(Fcount,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS  PreviousItemCount,
            CurrentItemDate, CurrentItemCount,
            LEAD(Datetype, 1) OVER (PARTITION BY Fname ORDER BY Datetype ASC) AS NextItemDate, 
            LEAD(Fcount,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS NextItemCount,
            SUM(Fcount) OVER(PARTITION BY Fname ORDER BY Datetype ) AS Total
    FROM FoodSara_tbl 
)
SELECT PreviousItemDate, PreviousItemCount, CurrentItemDate, CurrentItemCount,CurrentItemCount,NextItemCount, Total
FROM NextPreviousItemAndTotal

输入：

|PreviousItemDate|PreviousItemCount|CurrentItemDate|CurrentItemCount|NextItemDate|NextItemCount|
 |----------------|-----------------|---------------|----------------|------------|-------------|
 |   Null         |    Null         |   2019/10/10  |      10        |2019/10/12  |  2          |
 |   2019/10/10   |     10          |2019/10/12     |    2           |2020/01/20  |  12         |
 |  2019/10/12    |  12             |2020/01/20     |   12           |Null        |  Null       |

输出：

|PreviousItemDate|PreviousItemCount|CurrentItemDate|CurrentItemCount|NextItemDate|NextItemCount|Total|
 |----------------|-----------------|---------------|----------------|------------|-------------|-----|
 |   Null         |    Null         |   2019/10/10  |      10        |2019/10/12  |  2          |12   |
 |   2019/10/10   |     10          |2019/10/12     |    2           |2020/01/20  |  12         |24   |
 |  2019/10/12    |  12             |2020/01/20     |   8            |Null        |  Null       |20   |

【问题讨论】：

您希望该值是多少？什么逻辑定义total？您的查询还引用了许多不属于input 的列，这有点令人困惑。
是的，你是对的，我编辑了

标签： sql sql-server select common-table-expression

【解决方案1】：

如下使用coalesce：

Coalesce(PreviousItemCount,0) 
+ Coalesce(currentItemCount,0)
+ Coalesce(nextItemCount,0) as total

【讨论】：

【解决方案2】：

我更改了一些列的名称，但它会起作用

WITH 
NextPreviousItemAndTotal
AS
(
    SELECT LAG(Datetype, 1) OVER (PARTITION BY Fname ORDER BY Datetype ASC) AS PreviousItemDate,
            LAG(Fregion,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS PreviousRegion,
            LAG(Fcount,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS PreviousCount,
            Datetype, Fregion, Fname, Fcount,
            LEAD(Datetype, 1) OVER (PARTITION BY Fname ORDER BY Datetype ASC) AS NextItemDate, 
            LEAD(Fregion,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS NextItemRegion,
            LEAD(Fcount,1) OVER(PARTITION BY Fname ORDER BY Datetype) AS NextCount
            
    FROM FoodSara_tbl 
)
SELECT PreviousItemDate, PreviousRegion,PreviousCount, Datetype, Fregion, Fname, Fcount, NextItemDate, NextItemRegion,NextCount, Coalesce(PreviousCount,0) + Coalesce(Fcount,0)+ Coalesce(NextCount,0)AS Total
FROM NextPreviousItemAndTotal

【讨论】：