oracle中connect by prior的使用

https://www.cnblogs.com/wanggang-java/p/10916426.html#_labelTop
connect by主要用於父子，祖孫，上下級等層級關係的查詢

回到頂部
語法
{ CONNECT BY [ NOCYCLE ] condition [AND condition]… [ START WITH condition ]
| START WITH condition CONNECT BY [ NOCYCLE ] condition [AND condition]…}

– 創建表
create table employee(
emp_id number(18),
lead_id number(18),
emp_name varchar2(200),
salary number(10,2),
dept_no varchar2(8)
);

– 添加數據
insert into employee values(‘1’,0,‘king’,‘1000000.00’,‘001’);
insert into employee values(‘2’,1,‘jack’,‘50500.00’,‘002’);
insert into employee values(‘3’,1,‘arise’,‘60000.00’,‘003’);
insert into employee values(‘4’,2,‘scott’,‘30000.00’,‘002’);
insert into employee values(‘5’,2,‘tiger’,‘25000.00’,‘002’);
insert into employee values(‘6’,3,‘wudde’,‘23000.00’,‘003’);
insert into employee values(‘7’,3,‘joker’,‘21000.00’,‘003’);commit;

查詢以emp_id爲6開始的節點

   select emp_id,lead_id,emp_name,salary
   from employee 
   start with emp_id=6
   connect by prior lead_id=emp_id;
      **prior  後面是什麼就以這個條件找上級節點**