deletion with LINQ to SQL in visual studio

Question

I'm using LINQ to SQL in visual studio to interact with my database. Now I added methods that add, change etc to my code, but I cant make removing a row work. here is my remove method:

public bool removeUser(User toBeRemoved)
{
    try
    {
        theDBDataContext db = new theDBDataContext();
        UserDB u = new UserDB();
        u.username = toBeRemoved.userName;
        u.password = toBeRemoved.password;
        u.role = toBeRemoved.role;
        db.UserDBs.DeleteOnSubmit(u);
        db.SubmitChanges();
        return true;
    }
    catch (Exception e)
    {
        Log.writelog("Cannot Access DB");
        return false;
    }
}

Answer 1

You must attach the entity before delete:

    theDBDataContext db = new theDBDataContext();
    UserDB u = new UserDB();
    u.username = toBeRemoved.userName;
    u.password = toBeRemoved.password;
    u.role = toBeRemoved.role;
    db.Orders.Attach(u, false);
    db.UserDBs.DeleteOnSubmit(u);
    db.SubmitChanges();

See documentation here .

Answer 2

You can use extension method of Linq to delete the records.

    theDBDataContext db = new theDBDataContext();
     UserDB u = db.UserDBs.Where(u=>(u.username == toBeRemoved.userName & u.password == toBeRemoved.password & u.role==toBeRemoved.role)).FirstOrDefault(); 
     db.UserDBs.DeleteOnSubmit(u);
     db.SubmitChanges();