如何根据另一个 LINQ 查询过滤结果？

Question

鉴于以下情况：

    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 根据将 IsLead 位设置为 true 的leadEmployee 的人员列表正确过滤结果。

我想知道如何使用 where 子句来做到这一点，我曾尝试使用leadEmployees.Contanis，但它需要一个完整的 EmployeeRow ...

如何将看起来是 IN 子句的一部分添加到 where 过滤器以替换联接？

    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

如果您选择整个员工角色，则包含只需要整个 EmployeeRow。 您可以：

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

或者

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

两者都会起作用。 （请原谅稍微匆忙地缺乏对语法准确性的考虑）。

Answer 2

这应该有效：

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)
};