Hierarchy from Flat Data

Question

I have an employee class that has an employeeId (int), parent(int) and children property List. I get the employee list from the database in the

Answer 1

List allEmployees = new List();
allEmployees.AddRange(LoadAllEmployees()); // pull from DB in flat format    
foreach (var employee in allEmployees)
{
  employee.Children = allEmployees.Where(e => e.ParentId == employee.EmployeeId).ToList();
}