Sql 如何在同一个表中找到相同的值而不在where子句中硬编码？

我的桌子看起来像这样：

User  | Sale|  Year
-------------------------------
Kim   |  2  |  2019
Kim   |  2  |  2018
Kim   |  1  |  2017
Tim   |  3  |  2019
Tim   |  2  |  2018
Tim   |  1  |  2017
Jim   |  4  |  2019
Jim   |  3  |  2018
Jim   |  3  |  2017

Name | Current Year | Previous Years(Sum)
Kim  |      2       |       3
Tim  |      3       |       3
Jim  |      4       |       6 

表中有许多记录。 我想为每个用户添加过去几年的销售额

结果应该是这样的：

User  | Sale|  Year
-------------------------------
Kim   |  2  |  2019
Kim   |  2  |  2018
Kim   |  1  |  2017
Tim   |  3  |  2019
Tim   |  2  |  2018
Tim   |  1  |  2017
Jim   |  4  |  2019
Jim   |  3  |  2018
Jim   |  3  |  2017

Name | Current Year | Previous Years(Sum)
Kim  |      2       |       3
Tim  |      3       |       3
Jim  |      4       |       6 

到目前为止我已经试过了，但没有成功

select 
User,
Sale as CurrentYearSale,
sum(case when Year < 2019 then cast(Sale as int) end) as PreviousYearsSale
from 
Test 
where Year =2019
group by User,Sale;

---

您可以使用条件聚合：

select user,
       sum(case when year = 2019 then sales end) as current_year,
       sum(case when year < 2019 then sales end) as previous_years
from dummydata
group by user;

他是一把小提琴

如果不想硬编码年份，可以使用日期函数：

select user,
       sum(case when year = year(getdate()) then sales end) as current_year,
       sum(case when year < year(getdate()) then sales end) as previous_years
from dummydata
group by user;

---

尝试条件聚合，如下所示-

SELECT [User],
SUM(CASE WHEN [Year] = 2019 THEN Sale ELSE 0 END) C_year,
SUM(CASE WHEN [Year] < 2019 THEN Sale ELSE 0 END) P_year
FROM your_table
GROUP BY  [User]

你可以查一下

您给定的查询也应该写在下面-

select [User],
sum(case when [Year] = 2019 then cast(Sale as int) ELSE 0 end) as   CurrentYearSale,
sum(case when [Year] < 2019 then cast(Sale as int) ELSE 0 end) as PreviousYearsSale
from Test 
--where Year =2019
-- As your are calculating sum for previous year
-- you do not need to filter data by Year = 2019
group by [User];

---

您可以检查查询的输出

将条件聚合用作

SELECT UserName,
       SUM(CASE WHEN Year = 2019 THEN Sales ELSE 0 END) CurrYear,
       SUM(CASE WHEN Year < 2019 THEN Sales ELSE 0 END) PrevYears
FROM
(
  VALUES
  ('Kim',2, 2019),
  ('Kim',2, 2018),
  ('Kim',1, 2017),
  ('Tim',3, 2019),
  ('Tim',2, 2018),
  ('Tim',1, 2017),
  ('Jim',4, 2019),
  ('Jim',3, 2018),
  ('Jim',3, 2017)
) T(UserName, Sales, Year)
GROUP BY UserName;

---

您可以尝试这样的透视表

  --dummy data
    CREATE TABLE sales 
    (
        "user" varchar(10),
        sales int,
        "year" int,
    )

    drop table sales
    INSERT INTO dbo.sales  VALUES
        ('Kim',2, 2019),
      ('Kim',2, 2018),
      ('Kim',1, 2017),
      ('Tim',3, 2019),
      ('Tim',2, 2018),
      ('Tim',1, 2017),
      ('Jim',4, 2019),
      ('Jim',3, 2018),
      ('Jim',3, 2017)
    ------

    --- query

    select usr , current_year , previous_years
    from 

    (
        select "user" as usr , year,sum(sum_of_sales) as sum_of_sales
        from
        (
            select "user" , 
            case 
                when year = 2019 then 'current_year' 
                when year < 2019 then 'previous_years'
            end as year , 
            sum(sales) as sum_of_sales 
            from sales
            group by "user" , year  
        ) a
        group by "user" ,year


    )  as SourceTable
    pivot 
    (
    sum(sum_of_sales)  
    FOR year IN ( current_year , previous_years)  
    ) AS PivotTable; 

结果

---

我在上一年得到空值，当当前年份为2019年时，我在上一年得到的这些记录中又得到了3条记录sales@shah . . . 这正是问题所要求的。我添加了一个数据小提琴。我没有得到预期的结果，对于上一年的销售，我得到了3个额外的结果records@shah，这将为您提供预期的输出。你能检查一下这里的db小提琴吗？你试过你收到的答案了吗？是的，我试过了，但没有得到想要的结果。我用query的结果更新了问题。当我使用我的实际表而不是值时，它对我不起作用