使用Linq返回元素的id

Question

我有一个函数应该返回参数传递的元素的Id，例如：

public static Int32 getIdByName(string name)
{
    var query = from student in DataAccess.getInstance.StudentSet
                where student.FirstName.Equals(name)
                select student;

    return toto;
}

我不知道如何将结果toto转换为Int32并将其返回!!

Answer 1

return DataAccess.getInstance.StudentSet.Last(s => s.FirstName == name).Id;

Answer 2

public static Int32 getIdByName(string name)
{
    var query = from student in DataAccess.getInstance.StudentSet
                where student.FirstName.Equals(name)
                select student.Id;

    return query.First();
}