Linq 实现左连接，右连接

左连接：

var LeftJoin = from emp in ListOfEmployees
join dept in ListOfDepartment
on emp.DeptID equals dept.IDinto JoinedEmpDept
from dept in JoinedEmpDept.DefaultIfEmpty()
select new                         
{
EmployeeName = emp.Name,
DepartmentName = dept != null ? dept.Name : null                         
};

右连接：

var RightJoin =from dept in ListOfDepartment
join employee in ListOfEmployees
on dept.ID equals employee.DeptIDinto joinDeptEmp
from employee in joinDeptEmp.DefaultIfEmpty()
select new                           
{
EmployeeName = employee != null ? employee.Name :null,
DepartmentName = dept.Name
};