如何根据另一个 LINQ 查询过滤结果？

Question

Given the following:

    DP_DatabaseTableAdapters.EmployeeTableAdapter employeetableAdapter = new DP_DatabaseTableAdapters.EmployeeTableAdapter();
    DP_Database.EmployeeDataTable employeeTable = employeetableAdapter.GetData();

    var leadEmployees = from e in employeeTable
                        where e.IsLead == true
                        select e;

    DP_DatabaseTableAdapters.LaborTicketTableAdapter tableAdapter = new DP_DatabaseTableAdapters.LaborTicketTableAdapter();
    DP_Database.LaborTicketDataTable table = tableAdapter.GetDataByDate(date.ToString("MM/dd/yyyy"));

    var totHours = from l in table
                   join e in leadEmployees on l.EmployeeID equals e.EmployeeID
                   group l by l.EmployeeID into g
                   orderby g.Key
                   select new
                   {
                       EmployeeID = g.Key,
                       HoursWorked = g.Sum(s => s.HoursWorked)
                   };

Total hours correctly filters the results based on the leadEmployee's list of people who have the IsLead bit set to true.

I would like to know how to do this with a where clause, I have attempd to use leadEmployees.Contanis but it wants a whole EmployeeRow...

How can I add what looks to be part of an IN clause to a where filter to replace the join?

    var totHours = from l in table
                   where ??????
                   group l by l.EmployeeID into g
                   orderby g.Key
                   select new
                   {
                       EmployeeID = g.Key,
                       HoursWorked = g.Sum(s => s.HoursWorked)
                   };

Answer 1

The contains will only want a whole EmployeeRow if you are selecting whole employee roles. You can either:

leadEmployees.Select(e => e.id).contains

OR

leadEmployees.Count(e => e.id == l.id) > 0

Both will work. (Excuse slightly rushed lack of consideration for syntax accuracies).

Answer 2

This should work:

var leadEmployees = from e in employeeTable                        
where e.IsLead == true                        
select e.EmployeeID;

var totHours = from l in table                   
where leadEmployees.Contains(l.EmployeeID)             
group l by l.EmployeeID into g    
orderby g.Key
select new   
{                       
EmployeeID = g.Key,  
HoursWorked = g.Sum(s => s.HoursWorked)
};