```
public static bool StudentUpdate(string studentId)
{
    using (var db = new UniversityContext())
    {
        int idtoupdate = Convert.ToInt32(studentId);
        Student temp = db.Students.Where((a => a.Id) == idtoupdate)
                                  .SingleOrDefault();
        if (temp != null)
        {
            temp.FirstName = feilds[0];
            temp.LastName = feilds[1];
            temp.Average = Convert.ToSingle(feilds[2]);
            db.SaveChanges();
            return true;
        }
    }
    return false;
}

```

I need to update some information stored on a database using entity framework but when I try this code I get the following error message:

> 
> Operator '==' cannot be applied to operands of type 'lambda expression' and 'int'
> 
> 
> 

what can I do to solve this problem?