SQL语句递归查找

通过sql语句递归查找所有下级或上级用户

1.MS Sql

with cte as
(
    select Id,Pid,DeptName,0 as lvl from Department
    where Id = 2
    union all
    select d.Id,d.Pid,d.DeptName,lvl+1 from cte c inner join Department d
    on c.Id = d.Pid
)
select * from cte

2.Oracle

　一、建表

　　CREATE TABLE USERS.TBL_TEST

　　(

　　ID    NUMBER,

　　NAME  VARCHAR2(100 BYTE),

　　PID   NUMBER                                  DEFAULT 0

　　)

　　INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('1','10','0');

　　INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('2','11','1'

　　INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('3','20','0');

　　INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('4','12','1');

　　INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('5','121','2');

　　二、格式

　　Select * from …. Where [结果过滤条件语句]

　　Start with  [and起始条件过滤语句]

　　Connect by prior [and中间记录过滤条件语句]

　　三、查找所有下级

　　select * from tbl_test start with id=1 connect by prior id=pid

　　注意：此sql能查找id=1的数据的所有下级，写sql语句时要注意，因为是从id开始查找下级，所以connect by prior 子句的条件是id=pid

　　四、查找所有上级

　　select * from tbl_test start with id=5 connect by prior pid=id

　　因为是从id开始查找上级，所以connect by prior 子句的条件是pid=d