1、创建

create table USER
(ID   NUMBER(20) not null,constraint PK_USER primary key (ID)     //主键
);//添加注释
comment on table USER is '人员信息表';
comment on column USER.ID is '人员ID';

2、备份表

create table USER_temp as select * from USER;
--只取表结构，不取数据
create table USER_temp as select * from USER where 1=0;

3、删除表

drop table USER;

4、转移表数据

INSERT INTO USER
SELECT * FROM USER_temp;

5、查询数据库时间

select sysdate from dual;