linq中的两个别名求和

本文关键字：两个 别名 求和 linq | 更新日期: 2023-09-27 18:04:58

我用linq写这个查询，我想做这个工作在select new中对x和y求和2-时间跨度和多人播放，例如30

var query = 
    (from c in DB.SabtHoghoghs
     join aa in DB.SabtHesabKarmands on c.KarmandID equals aa.KarmandID
     select new 
        { 
            c.Karmand.FName,
            c.BabatMah,
            x = DB.SabtHesabKarmands.Where(q => q.BabatMah.Year == c.BabatMah.Year &&
                q.BabatMah.Month == c.BabatMah.Month && q.HesabKarmand.HesabKarmandTypeID==1)
                .Sum(aaa => aaa.Tedad * aaa.HesabKarmand.Mablagh),
            y = DB.SabtHesabKarmands.Where(q => q.BabatMah.Year == c.BabatMah.Year &&
                q.BabatMah.Month == c.BabatMah.Month && q.HesabKarmand.HesabKarmandTypeID == 2)
                .Sum(aaa => aaa.Tedad * aaa.HesabKarmand.Mablagh),
            z=y-x   //how to do this(1)
            karkard = (c.Karmand.ExitTime-c.Karmand.EnterTime).Hours *30  //how to do this(2)
        }).Distinct();

linq中的两个别名求和

在查询中使用let关键字:

var query =
(from c in DB.SabtHoghoghs
join aa in DB.SabtHesabKarmands on c.KarmandID equals aa.KarmandID
let x = DB.SabtHesabKarmands.Where(q => q.BabatMah.Year == c.BabatMah.Year &&
        q.BabatMah.Month == c.BabatMah.Month && q.HesabKarmand.HesabKarmandTypeID == 1)
        .Sum(aaa => aaa.Tedad * aaa.HesabKarmand.Mablagh)
let y = DB.SabtHesabKarmands.Where(q => q.BabatMah.Year == c.BabatMah.Year &&
        q.BabatMah.Month == c.BabatMah.Month && q.HesabKarmand.HesabKarmandTypeID == 2)
        .Sum(aaa => aaa.Tedad * aaa.HesabKarmand.Mablagh)
select new
{
    c.Karmand.FName,
    c.BabatMah,
    X = x,
    Y = y,
    Z = y - x,   //how to do this(1)
    karkard = (c.Karmand.ExitTime - c.Karmand.EnterTime).Hours * 30  //how to do this(2)
}).Distinct();

我将尽力指导你找到正确的解决方案。定义自定义类，不要使用匿名类，像这样

class MyClass
{
    public string FName { get; set; }
    public string BabatMah { get; set; }
    public int x { get; set; }
    public int y { get; set; }
    public int z { get { return x - y; }    }
    public int karkard { get; set; }
    // implement Equals and GetHashCode for correct behaviour of Distinct
}

然后选择不含z的计算值进入MyClass 

select new MyClass
    { 
        FName = c.Karmand.FName,
        BabatMah = c.BabatMah,
        ...

为了解决(c.Karmand.ExitTime-c.Karmand.EnterTime).Hours *30计算，您需要带来有关ORM的更多细节。解决方案将视情况而定。一种通用的解决方案是将ExitTime和EnterTime提取到MyClass中，然后以相同的方式计算小时差，就像计算x - y

一样。
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