小编bog*_*diu的帖子

如何在SQL Server中将二进制文件(128)从小端转换为大端？

如何在EF 4.0 FluentAPI CTP5中映射0..1到*关系？我一直在犯这个错误

由于"从属角色"中的所有属性都是不可为空的,因此"主体角色"的多重性必须为"1".

我不知道如何解决它..

我的代码看起来像这样

    public class Child{
        public int pID { get; set; }
        public Parent Parent_Object{ get; set; } 
        public int Parent{ get; set; } 

        public Child() {
        }
    }


    public class Parent {
        public int pID { get; set; }
        public List<Child>  Children { get; set; }

        public Parent () {
        }
    }

对于映射,代码看起来像这样

modelBuilder.Entity<Child>().HasKey(c=> c.pID);  
modelBuilder.Entity<Parent>().HasKey(c=> c.pID); 
modelBuilder.Entity<Child>().HasOptional(c=> c.Parent_Object)
                            .WithMany(p => p.Children)
                            .HasForeignKey(p => p.Parent);

也有可能只有

public Parent Parent{ get; set; } 

代替

public …

我有一个树类结构的类,树中的树节点有产品,产品有Cods我需要选择所有顶级类别(parent = null),叶子(Cods)匹配一些标准...

SELECT  
    Category.Id AS Id0_, 
    Category.Name AS Name0_, 
    Category.COrder AS COrder0_, 
    Category.Description AS Descript4_0_, 
    Category.ParentId AS ParentId0_, 
    Category.Description_En AS Descript6_0_, 
    Category.Name_En AS Name_En0_, 
    Category.ImagePath AS ImagePath0_ 
FROM
    Category 
    LEFT JOIN Category AS c1 ON Category.Id=c1.ParentId
    LEFT JOIN Category AS c2 ON c1.Id=c2.ParentId
    LEFT JOIN Category AS c3 ON c2.Id=c3.ParentId
    LEFT JOIN Category AS c4 ON c3.Id=c4.ParentId
    LEFT JOIN Product ON 
        c4.Id=Product.Category 
        OR c3.Id=Product.Category 
        OR c2.Id=Product.Category 
        OR c1.Id=Product.Category 
        OR Category.Id=Product.Category
    INNER JOIN Cod ON Cod.Product=Product.Id   
WHERE
    Category.ParentId is null …