Oracle中connect by prior .... start with

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一 connect by prior ....start with
 废话少说上测试代码.
        

create table test_table_c(id number primary key,description varchar(255),parent_id number);
insert into test_table_c(id,description,parent_id) values(1,'cuiyaonan2',null);
insert into test_table_c(id,description,parent_id) values(2,'cuiyaonan20',1);
insert into test_table_c(id,description,parent_id) values(3,'cuiyaonan200',2);
insert into test_table_c(id,description,parent_id) values(4,'cuiyaonan2000',3);
insert into test_table_c(id,description,parent_id) values(5,'cuiyaonan2000@',4);
insert into test_table_c(id,description,parent_id) values(6,'cuiyaonan2000@1',5);
insert into test_table_c(id,description,parent_id) values(7,'cuiyaonan2000@16',6);
　　显示结果为
　　


 
 
执行语句
 

select * from test_table_c connect by prior parent_id  =  id  start with id =7;
　　显示结果为:
　　


 
 
执行语句
 

select * from test_table_c connect by parent_id  =  prior id  start with id =1;
　　显示结果
　　


 
 
注释 :prior  表示上一条记录. prior +字段 表示上一条记录的某个字段.如 

parent_id  =  prior id
表示上一条记录的id与本条记录的parent_id值是否一致.