<span >create table tb_user (
   userId             INTEGER                         not null,
   userName           CHAR(20),
   constraint PK_TB_USER primary key (userId)
)</span>

<span >create sequence tb_user_id
increment by 1
start with 0
 maxvalue 10000
 minvalue 0
nocycle
 cache 20
order;</span>

<span >insert into tb_user(userId,userName) values(tb_user_id.nextval,'刘云生')</span>