没有定义主键，也无法推断出有效的主键

Question

I have this query in making my view but the problem is this view is not included in my Model. So, I could not use this view.

Here is my code:

CREATE VIEW [dbo].[Payment_Transaction_vw]
AS 
    SELECT 
        id = ROW_NUMBER() OVER (ORDER BY (SELECT NULL)),
        Transaction_Info.trans_name, Student_Info.ID_Number,
        Student_Info.student_fname, Student_Info.student_lname,
        SUM(Payment_Transaction.amount) AS amount
    FROM 
        [Payment_Transaction]
    INNER JOIN 
        Student_Info ON Payment_Transaction.student_info_id = Student_Info.student_info_id 
    INNER JOIN 
        Transaction_Info ON Payment_Transaction.trans_info_id = Transaction_Info.trans_info_id 
    GROUP BY 
        ID_Number, student_lname, student_fname, trans_name;

This view can be seen in the database after I create this. But not when I add a model. This is not included in my Entity.

Here is the error will displayed:

dbo.Payment_Transaction_vw does not have a primary key defined and no valid primary key could be inferred. This table/view has been excluded. To use the entity, you will need to review our schema, add the correct keys, and uncomment it.

Please help me with this matter. Thanks in advance.

Answer 1

I think it might be because EF has a hard time choosing the correct primary key. A way to force EF to choose a key of your liking seems to be to use ISNULL() for the primary key, and NULLIF() for the other columns (at least the ones that could cause confusion, like primary keys from other tables or non-nullable columns).

In your case this would mean:

SELECT 
    ISNULL(ROW_NUMBER() OVER(ORDER BY (SELECT NULL)), -1) AS Id,
    NULLIF(Transaction_Info.trans_name,'') AS trans_name, 
    NULLIF(Student_Info.ID_Number,-1) AS ID_Number,
    NULLIF(Student_Info.student_fname,'') AS student_fname, 
    NULLIF(Student_Info.student_lname,'') AS student_lname,
    NULLIF(SUM(Payment_Transaction.amount),-1) AS amount
FROM [Payment_Transaction]
INNER JOIN Student_Info ON 
    Payment_Transaction.student_info_id = Student_Info.student_info_id 
INNER JOIN Transaction_Info ON 
    Payment_Transaction.trans_info_id = Transaction_Info.trans_info_id 
GROUP BY ID_Number, student_lname, student_fname, trans_name;

You probably don't need all these NULLIF() 's, but since I'm not sure what column is causing issues it's better to take all. If it works with this code, you can start removing the NULLIF from student names and trans_name .

Answer 2

您需要定义第一个id列主键mvc在与模型一起使用时不允许这样做