如何根據另一個 LINQ 查詢過濾結果？

Question

鑒於以下情況：

    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 根據將 IsLead 位設置為 true 的leadEmployee 的人員列表正確過濾結果。

我想知道如何使用 where 子句來做到這一點，我曾嘗試使用leadEmployees.Contanis，但它需要一個完整的 EmployeeRow ...

如何將看起來是 IN 子句的一部分添加到 where 過濾器以替換聯接？

    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

如果您選擇整個員工角色，則包含只需要整個 EmployeeRow。 您可以：

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

或者

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

兩者都會起作用。 （請原諒稍微匆忙地缺乏對語法准確性的考慮）。

Answer 2

這應該有效：

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)
};