实体框架6向SQL发送查询时生成额外的联接

Question

This is my framework that develop by entityframework 6:

User DataModel :

[DataContract]
[Table("SEC_User")]
public class UserDataModel : EntityBase
{
    [DataMember]
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Column("UserID")]
    public int UserID{get;set;}

    [DataMember]
    [Column("UserName")]
    public string UserName{get;set;}

    [DataMember]
    [Column("UserKindRef")]
    public int UserKindRef{get;set;}
    .
    .
    .
}
[DataContract]
[Table("SEC_User_View")]
public class UserViewDataModel : UserDataModel
{
    [DataMember]
    [Column("UserKindTitle")]
    public string UserKindTitle{get;set;}        
}

DataAccess Method:

public UserViewDataModel GetByUserName(string userName)
    {
       using (Context)
       {
        return (from entity in Context.EntityList
                 where entity.UserName == userName
                 select entity).FirstOrDefault().ToEntity();
       }
    }

Sql Profiler :

exec sp_executesql N'SELECT 
[Limit1].[C1] AS [C1], 
[Limit1].[UserID] AS [UserID], 
[Limit1].[UserName] AS [UserName], 
[Limit1].[UserKindRef] AS [UserKindRef], 
[Limit1].[UserKindTitle] AS [UserKindTitle]
FROM ( SELECT TOP (1) 
    [Extent1].[UserKindTitle] AS [UserKindTitle], 
    [Extent2].[UserID] AS [UserID], 
    [Extent2].[UserName] AS [UserName], 
    [Extent2].[UserKindRef] AS [UserKindRef], 
    ''0X0X'' AS [C1]
    FROM  [dbo].[SEC_User_View] AS [Extent1]
    INNER JOIN [dbo].[SEC_User] AS [Extent2] ON [Extent1].[UserKey] =[Extent2].[UserKey]
    WHERE ([Extent2].[UserName] = @p__linq__0) OR (([Extent2].[UserName] IS NULL) AND (@p__linq__0 IS NULL))
)  AS [Limit1]',N'@p__linq__0 nvarchar(4000)',@p__linq__0=N'admin'

Unfortunately when UserViweDataModel Inherited from UserDataModel entityframework , entityframework use select to select and join SEC_User_View to SEC_User and it's wrong. It should be like this:

exec sp_executesql N'SELECT TOP (1) 
[Extent1].[UserID] AS [UserID], 
[Extent1].[UserName] AS [UserName], 
[Extent1].[UserKindRef] AS [UserKindRef], 
[Extent1].[UserKindTitle] AS [UserKindTitle]
FROM [dbo].[SEC_User_View] AS [Extent1]
WHERE ([Extent1].[UserName] = @p__linq__0) OR (([Extent1].[UserName] IS NULL) AND (@p__linq__0 IS NULL))',N'@p__linq__0 nvarchar(4000)',@p__linq__0=N'admin'

what's my mistake????

Answer 1

Table(SEC_User) and Table(SEC_User_View) . You told EF you wanted two tables.

Inheritance with EF: Table Per Hierarchy

The default for EF is TPH, but – by decorating both classes with Table – you told it you want TPT (see part 2 of the blog article I posted above).

BTW, if you do want TPH – which it sounds like you do – the one and only table is going to be the base class, not the derived.