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.ID into 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.DeptID into joinDeptEmp
from employee in joinDeptEmp.DefaultIfEmpty()
select new                            
{
EmployeeName = employee != null ? employee.Name : null,
DepartmentName = dept.Name
};