LINQ的SQL命令(透视) [英] SQL command to LINQ (pivoting)

问题描述

我正在将数据库从MySQL(使用的ODBC)转移到MS SQL，我想将SQL查询翻译"到LINQ.有人可以帮我吗(每个位置的SUM收费列和按月分组的结果):

I'm moving DB from MySQL (used ODBC) to MS SQL and I want to "translate" SQL queries to LINQ. Can someone help me with this (it should SUM Charge column for every location and group result by months):

SELECT
sum(case when Location="Location1" then Charge else 0 end) as Location1,
sum(case when Location="Location2" then Charge else 0 end) as Location2,
sum(case when Location="Location3" then Charge else 0 end) as Location3,
MAKEDATE(YEAR(OrderTime),DAYOFYEAR(OrderTime)) AS date FROM Sales
GROUP BY YEAR(OrderTime),MONTH(OrderTime)
ORDER BY OrderTime DESC 

?

输出应如下所示:

Location1 | Location2 | Location3 | date

我尝试从这里使用LINQ示例:

I tryed to use LINQ sample from here:

是否可以使用LINQ进行数据透视?

var query = context.log_sales
                            .GroupBy(c => c.OrderTime)
                            .Select(g => new
                            {
                                Date = g.Key,
                                Location1 = g.Where(c => c.Location == "Location1").Sum(c => c.Charge) ?? 0,
                                Location2 = g.Where(c => c.Location == "Location2").Sum(c => c.Charge) ?? 0
                            }).ToList();

这几乎是我所需要的.也应该按年份分组，我不知道该怎么做.

and it is almost what I need. There should be grouping by year too and I don't know how to do this.

推荐答案

这可能有帮助.

context.log_sales
.GroupBy(s => new {Year = OrderTime.Year, Month = OrderTime.Month})
.Select
( g => new {
  Date = new DateTime(g.Key.Year, g.Key.Month, 1),
  Location1 = g.Where(s => s.Location == "Location1").Sum(s => s.Charge),
  Location2 = g.Where(s => s.Location == "Location2").Sum(s => s.Charge),
  Location3 = g.Where(s => s.Location == "Location3").Sum(s => s.Charge),
  }
)
.OrderBy(x => x.Date);

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