寻找更好的方法来通过 ID 获取项目集合

Question

我有一个非常标准的设置，部门和员工之间有多对多的关系。

Departments
---------------
DepartmentID
Name

Employees
---------------
EmployeeID
Name

DepartmentEmployees
-------------------
DepartmentID
EmployeeID

给定一个部门，我想返回该部门的员工列表。这就是我所拥有的：

public partial class Department
{
    public List<Employee> GetEmployees()
    {
        int[] employeeIds = MyDBDataContext.DepartmentEmployees.
                            Where(de => de.DepartmentID == this.DepartmentID).
                            Select(de => de.EmployeeID.Value).ToArray();

        List<Employee> employees = (from x in MyDBDataContext.Employees
                                    where employeeIds.Contains(x.EmployeeID)
                                    select x).ToList();

        return employees;
    }
}

这工作正常，但我不喜欢进行两个数据库调用。还有其他方法可以使用 LINQ 实现此目的吗？

Answer 1

为什么不使用连接？

var employees = (from e in MyDBDataContext.Employees
                 join de in MyDBDataContext.DepartmentEmployees
                     on e.EmployeeID equals de.EmployeeID
                 where de.DepartmentID == this.DepartmentID
                 select e).ToList();