我需要在我的数据库中计算一列作为 (行和) - (行b和),我正在使用代码优先模型来创建我的数据库。
这是我的意思:
public class Income {
[Key]
public int UserID { get; set; }
public double inSum { get; set; }
}
public class Outcome {
[Key]
public int UserID { get; set; }
public double outSum { get; set; }
}
public class FirstTable {
[Key]
public int UserID { get; set; }
public double Sum { get; set; }
// This needs to be calculated by DB as
// ( Select sum(inSum) FROM Income WHERE UserID = this.UserID)
// - (Select sum(outSum) FROM Outcome WHERE UserID = this.UserID)
}
如何在EF CodeFirst中实现这个?