SQL LEVEL 自动分等级

drop table TB_CLASS cascade constraints;

/*==============================================================*/
/* Table: TB_CLASS                                              */
/*==============================================================*/
create table TB_CLASS  (
   ID                   NUMBER(16)                      not null,
   NAME                 VARCHAR2(30),
   PID                  NUMBER(16)                      not null,
   SORT                 NUMBER(16),
   constraint PK_TB_CLASS primary key (ID)
);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (1, '购物', 0, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (2, '球具', 1, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (3, '球包', 1, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (4, '高尔夫球', 1, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (5, '球杆', 2, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (6, '一号木', 2, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (7, '铁木干', 2, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (8, 'Titleist球', 4, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (9, '高尔夫鞋', 1, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (10, '男士鞋', 9, null);

insert into TB_CLASS (ID, NAME, PID, SORT)
values (11, '女士鞋', 9, null);

SELECT B.ID,
       B.NAME,
       LEVEL
  FROM TB_CLASS B
 START WITH B.PID = 0
CONNECT BY PRIOR B.ID = B.PID