Oracle学习笔记(四)

豆蔻年华、调节顾客存取 1、创制改革客商Creating Users Create/alter user
new_www.6766.com ,user identified by password; 例:create user user_1 indentified by
pwd_1 alter user user_1 identified by pwd_2 2、给顾客付与权限 grant
privilege[,privilege] to user [,user|role,public…] 一些系统权限:
create session/table/sequence/view/procedure
alter/delete/execute/index/insert/references/select/update grant
object_priv [(columns)] on object to {user|role|public} [with grant
option] 例如: 给用户user_1给与查询tt1表的权柄 grant select on tt1表 to
user_1 给用户user_1付与改革“表1”中(列1,列2卡塔尔国的权杖 grant
update(列1,列2卡塔尔(قطر‎ on 表1 to user_1; 给用户user_1
授予查询权限并得以把该权限付与别的顾客的权限 grant select on tt1表 to
user_1 with grant option 把权限付与全部客户 grant select on 表1 to
public; 给客户user_1授权 grant create session to user_1;
二、成立剧中人物并给剧中人物授权 1、创制角色 create role mangager;
例如:create role test_role1; 2、给角色授权 grant create table,create
view to manager; 举例:grant create table to test_role1;
3、把角色授予客户 grant manager to user_1,user_2… grant test_user1
to user_Oracle学习笔记(四)。1; 三、废除顾客权限 revoke {privilege
[,privilege…]|all} on object from {user[,user…]|role|public}
[cascade constraints]; revoke select on 表1 from user_1;
四、Database Links create public database link hq.acme.com using
‘sales’; select * from emp@hq.acme.com; 五、
oracle取并集、交集、差集
所取的列的数据类型必需协作 1、取并集 union
:会对数码排序,重复记录压缩,union all不会 select employee_id,job_id
from employess union select employee_id,job_id from job_history;
取全数并集不去除重复数据 select employee_id,job_id from employess
union all select employee_id,job_id from job_history; 2、取交集
select employee_id,job_id from employess intersect select
employee_id,job_id from job_history; 3、差集
表employess去掉协同全部的多寡 select employee_id,job_id from employess
minus select employee_id,job_id from job_history;
六、日期时间函数 求时差 select tz_offset(‘US/Eastern’) from dual;
alter session set time_zone=’-8:0′; select
sessiontimezone,current_date from dual; alter session set
time_zone=’-8:0′; select sessiontimezone,current_timestamp from dual;
alter session set time_zone=’-8:0′; select
current_timestamp,localtimestamp from dual; select
dbtimezone,sessiontimezone from dual; select
from_tz(timestamp’2000-03-23 08:00:00′,’3:00′) from dual; select
to_timestamp(‘2000-02-01 11:00:00′,’YYYY-MM-DD HH:MI:SS’)from dual;
select to_timestamp_tz(‘2000-02-01 11:00:00′,’YYYY-MM-DD HH:MI:SS
TZH:TZM’)from dual; to_ymininterval()

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