1.oracle architecture
-------- global database, this refers to the database (physical structure, a real disk directory) on a physical disk, a general oracle server has 1 Ge global database, file accounts for 1G and more. oracle allows a
-------- one computer to install multiple global database, but this is not recommended. Because a global database can put all the data.
-------- here and mysql is not the same, mysql is free to create a database. A global database comprising N plurality of data files.
-------- users, the oracle which is to isolate the data, MySQL isolating database data units, and oracle unit of user data isolation.
-------- table space is a logical structure, user data is stored in the space table, the data table space is in the data file. Table space may be logically
-------- to the data file into a plurality of regions, each region is a table space. The data file is composed of more than one table space.
-------- data file, which is a global database data files (physical structure, a real disk file). A global database comprising N plurality of data files.
-------- Database Services instance (database instance), is a service process for executing sql command to change to update the data files.
-2. Use oracle access data in step
The first 1 : Create table space
- Creating syntax:
create tablespace table space name
datafile ' disk data file address ' size data file size
autoextend on next automatically grow in size
- Examples
create tablespace itheima91
datafile ‘c:\itheima91.dbf’ size 100m
autoextend on next 10m
The first 2 steps: Create a user
- Creating syntax:
create user username identified by password
default tablespace table space name ;
- Examples
create user ith identified by itheima91
default tablespace itheima91;
- Use a new user logs to try: the results can not log on, because access is not enough
The first 3 steps: Authorization
- Syntax 1
grant permissions 1, permission 2, ... to the user name ;
- Syntax 2
grant Role 1, Role 2, ... to the user name ;
- role, a role contains multiple permissions
-Oracle system built 3 Ge is, Connect, Resource, dba
------- connect roles, connected to the oracle of authority
------- resource role, operating their own data objects (create your own table, inside the CRUD data), can not operate other user data
------- dba role, the Super Administrator role, the current system is dba. have all privileges
- For convenience, dba given to the user
grant dba to itheima91;
------------------------- at itheima91 / itheima91 Sign follows ----------------- --------------------
select * from session_privs; - view the current user belongs to role permissions list, dba has 161 Ge rights
SELECT * FROM USER_ROLE_PRIVS; - view the current user belongs to role
3. The management table create, drop, alter
Create table Syntax:
grammar:
create table 表名(
Field 1 Data Type [default Default ]
Field 2 Data type [default Default ]
…
Field n Data type [default Default ]
);
- Create a person table
create table person(
id number(8) primary key,
name varchar2(100) not null,
gender varchar2(2),
birthday date
);
Table deleted
- mode 1 : Delete table data
delete from person;
- mode 2 : Table Structure removed
drop table person;
Table modification
- add a field
alter table person add (address varchar2(100));
- modify the field name
alter table person rename column address to address2;
- modify the field data type
alter table person modify (address2 varchar2(200));
Update the table (add, delete, change)
4 Data management: the Delete, Update, the SELECT, INSERT INTO
- Delete
delete from person where id=2;
- Modify
update person set address2=‘东莞’ where id=1;
- Query
select * from person;
- increase the data
insert into person(id,name,gender,birthday,address2)
values (1, ' John Doe ', ' M ', to_date ( '2018-01-01', 'yyyy-MM-dd HH24: mi: ss'), ' Canton ');
insert into person
values (2, ' John Doe ', ' F ', to_date ( '2018-01-01', 'yyyy-MM-dd HH24: mi: ss'), ' Shenzhen ');
-Oracle have mechanisms things, things that need to be submitted for each add, delete, change data manually.