U-SQL

Question

我有一个 table 客户交易，我试图按客户和部门汇总。

Cust_id    trans_num    sku   dept   qty    price
 123         234        345    1      2      15.99
 123         345        887    1      1      12.99
 123         678        445    2      1      21.89
 234         345        998    1      1       7.99

在 SQL 我会做这样的事情：

SELECT Cust_id
         , SUM(CASE WHEN dept = 1 THEN (price * qty) ELSE 0 END ) dept_1_spend
         , SUM(CASE WHEN dept = 2 THEN (price * qty) ELSE 0 END ) dept_2_spend
from tab1
group by Cust_id

U-SQL 文档 here 提到 ? 作为 C# 等价物，但我不确定如何 SUM 值。

U-SQL 中的等价物是什么？

Answer 1

您可以在 C# 中尝试三元运算符：

SELECT Cust_id
         , SUM(dept == 1 ? price * qty : 0) AS dept_1_spend
         , SUM(dept == 2 ? price * qty : 0) AS dept_2_spend
from tab1
group by Cust_id

Answer 2

您甚至可以使用 SQL 的 CASE 表达式。您将需要 C# == 并使用 AS 来指定列别名并为关键字使用大写字母。但在其他方面看起来像您的查询：

@tab1 =
  SELECT *
  FROM(
  VALUES
    (123,234,345,1,2,15.99),
    (123,345,887,1,1,12.99),
    (123,678,445,2,1,21.89),
    (234,345,998,1,1,7.99)) AS T(Cust_id,trans_num,sku,dept,qty,price);

@res =
  SELECT Cust_id,
         SUM(CASE WHEN dept == 1 THEN(price * qty) ELSE 0 END) AS dept_1_spend,
         SUM(CASE WHEN dept == 2 THEN(price * qty) ELSE 0 END) AS dept_2_spend
  FROM @tab1
  GROUP BY Cust_id;

OUTPUT @res
TO "/output/sum_case.csv"
USING Outputters.Csv();

我个人更喜欢 C# 三元 if。

Answer 3

您也可以使用 U-SQL PIVOT 运算符，例如

@tab1 =
  SELECT *
  FROM(
  VALUES
    (123,234,345,1,2,15.99),
    (123,345,887,1,1,12.99),
    (123,678,445,2,1,21.89),
    (234,345,998,1,1,7.99)) AS T(Cust_id,trans_num,sku,dept,qty,price);


@res =
    SELECT Cust_id,
           SUM([1]) AS dept_1_spend,
           SUM([2]) AS dept_2_spend
    FROM
    (
        SELECT Cust_id, dept, price * qty AS spend
        FROM @tab1
    ) AS t
    PIVOT (SUM(spend) FOR dept IN ( 1 AS [1], 2 AS [2] )
    ) AS pvt
    GROUP BY Cust_id;


OUTPUT @res
TO "/output/sum_case.csv"
USING Outputters.Csv();

有关 U-SQL PIVOT 的更多信息可用 here。

U-SQL - CASE 语句的 SUM

U-SQL - SUM of a CASE Statement

c#

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