alter/delete/execute/index/insert/references/select/update
select * from [email protected];
union all
select from_tz(timestamp'2000-03-23 08:00:00','3:00') from dual;
alter session set time_zone='-8:0';
select sessiontimezone,current_timestamp from dual;
select to_timestamp_tz('2000-02-01 11:00:00','YYYY-MM-DD HH:MI:SS TZH:TZM')from dual;
create session/table/sequence/view/procedure
union
revoke {privilege [,privilege...]|all}
union ：会对数据排序，重复记录压缩，union all不会
[cascade constraints];
minus

to public;
[with grant option]
select employee_id,job_id from job_history;
grant object_priv [(columns)]
select sessiontimezone,current_date from dual;
3、差集

五、 oracle取并集、交集、差集
2、给角色授权
一些系统权限：
六、日期时间函数
Create/alter user new_user identified by password;
select to_timestamp('2000-02-01 11:00:00','YYYY-MM-DD HH:MI:SS')from dual;



例如:
to {user|role|public}
1、创建角色

例如：grant create table to test_role1;
select employee_id,job_id from employess
1、取并集


select employee_id,job_id from job_history;
select dbtimezone,sessiontimezone from dual;
to_ymininterval()

一、控制用户存取
grant test_user1 to user_1;

二、创建角色并给角色授权
给用户user_1 授予查询权限并可以把该权限授予其他用户的权限
grant select
2、取交集
取所有并集不去除重复数据
grant create session to user_1;
select tz_offset('US/Eastern') from dual;
grant create table,create view to manager;
select employee_id,job_id from employess
三、取消用户权限
on object
with grant option
例如：create role test_role1;
给用户user_1授权
2、给用户授予权限
把权限授予所有用户

例：create user user_1 indentified by pwd_1
select employee_id,job_id from employess
求时差
alter user user_1 identified by pwd_2
create public database link hq.acme.com using 'sales';
给用户user_1授予修改“表1”中(列1，列2)的权限
revoke select on 表1 from user_1;
grant select
给用户user_1授予查询tt1表的权限

表employess去掉共同拥有的数据

create role mangager;
select current_timestamp,localtimestamp from dual;