Question

我在TSQL中有一个查询，我试图将其转换为LINQ以便在我们的Web应用程序中使用，但我真的在努力解决这个问题。它是带有EF6的MVC5，数据库是SQL Server 2008 R2。任何帮助表示赞赏！

SQL查询

select MAX(ShipFromCompanyName) as Supplier, COUNT(*) as AllSupplierCount, 
SUM(isnull(cast(TransportationCharges as decimal(18,2)),0)) as AllFreightCharges,
SUM(isnull(cast(TransportationCharges as decimal(18,2)),0)) * .45 as FreightSavings
from table
group by ShipFromCompanyName
order by ShipFromCompanyName

ShipFromCompanyName和TransportationCharges都作为varchar存储在数据库中，遗憾的是我无法将TransportationCharge的数据类型更改为小数

LINQ

var Scorecard = (from upsid in _db.table select upsid).GroupBy(x => new { x.ShipFromCompanyName, x.TransportationCharges })
            .Select(x => new
            {
                x.Key.ShipFromCompanyName,
                SupplierCount = x.Count(),
                FreightCharges = x.Key.TransportationCharges.Cast<decimal>().Sum(),
            }).ToList();

Answer 1

我认为您需要在处理后进行操作，而不是让SQL执行此操作。让SQL做尽可能多的事情然后在内存中做其余的事情

var Scorecard = (from upsid in _db.table select upsid).GroupBy(x => new { x.ShipFromCompanyName, x.TransportationCharges })
        .Select(x => new
        {
            x.Key.ShipFromCompanyName,
            SupplierCount = x.Count(),
            FreightCharges = x.Key.TransportationCharges,
        }).AsEnumerable()
        .Select (x => new 
        {
            ShipFromCompanyName = ShipFromCompanyName ,
            SupplierCount = SupplierCount ,
            FreightCharges = FreightCharges.Cast<decimal>.Sum() ,
        }

没有测试过这段代码，但它应该会给你一个想法。

Answer 2

var Scorecard = (from upsid in _db.table select upsid)
.GroupBy(x => new { x.ShipFromCompanyName, x.TransportationCharges })
.Select(x => new
{
    x.Key.ShipFromCompanyName,
    SupplierCount = x.Count(),
    FreightCharges = x.Key.TransportationCharges.Select(tc=>decimal.Parse(tc)).Sum()*0.45,
}).ToList();

由于我不明白你的查询我不确定，但这可能有用。

将SQL Query转换为LINQ以用于应用程序

2 个答案: