T-SQL:CTE实现递归

USE AdventureWorks ;
GO
WITH DirectReports(LoginID, ManagerID, EmployeeID) AS
(
    SELECT LoginID, ManagerID, EmployeeID
    FROM HumanResources.Employee
    WHERE ManagerID IS NULL
    UNION ALL
    SELECT e.LoginID, e.ManagerID, e.EmployeeID
    FROM HumanResources.Employee e
    INNER JOIN DirectReports d
    ON e.ManagerID = d.EmployeeID
)
SELECT *
FROM DirectReports;
OPTION (MAXRECURSION 3);