使用LINQ to SQL更新外键相关记录

Question

I am working on application with more than 50 tables with a large amount of data.

Let's say I have two tables:

Parent { pID int (PK), pName varchar(30) }

and

Child { pID int (FK), cName varchar(30) }

Here is my query:

using(MyDBContext ctx = new MyDBContext())
{
    Child ch = ctx.Childs.Where( c => c.pID == 1).FirstOrDefault();
    ch.cName = "ABCDEF";
    ctx.SubmitChanges();   //  <--- Executes but nothing changes...
}

I have tried multiple existing values but ctx.SubmitChanges() doesn't work when updating child record. Any workaround?

Answer 1

The table could not be updated, because it doesn't have primary key. SubmitChanges will not work if you dont have primary key on your table(child). Set primary key on Child table like this

Child { ID int (PK), pID int (FK), cName varchar(30) }

and may everething will by ok

Answer 2

I have found a solution by myself. I have created an SQL Procedure which updates the record. Here is, how I did it:

create procedure UpdateChildName
(
    @pID int,
    @name varchar(30)
)
AS
BEGIN
    update Child set cName = @name where pID = @pID;
END;

Linq to SQL Part:

using(MyDBContext ctx = new MyDBContext())
{
    ctx.UpdateChildName(1, "ABCDE");
    ctx.SubmitChanges();         //   <--- Now working great.
};

Now, I don't have any issue with FK or PK dependency... :)