学习目标
学习openGauss数据库、用户和模式的关系和访问方式，理解模式是在数据库层面，用户是在实例层面
课程学习
一个用户连接到数据库后，可以在这个数据库中创建多个模式。要访问这些模式，可以使用DatabaseName.SchemaName.TableName或者SchemaName.TableName，来访问某个模式下的一个表。
默认情况下访问public模式下的表，可以不用添加模式名前缀。
课程作业
1.查看当前数据库下有哪些模式
--进入默认数据库omm，创建表空间、测试数据库
/*
DROP DATABASE IF EXISTS musicdb;
DROP DATABASE IF EXISTS musicdb1;
DROP DATABASE IF EXISTS musicdb2;
DROP DATABASE IF EXISTS musicdb3;
DROP tablespace IF EXISTS music_tbs;
CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
*/
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# DROP DATABASE IF EXISTS musicdb;
DROP DATABASE
omm=# DROP DATABASE IF EXISTS musicdb1;
DROP DATABASE IF EXISTS musicdb2;
DROP DATABASE
omm=# DROP DATABASE
omm=# DROP DATABASE IF EXISTS musicdb3;
DROP DATABASE
omm=# DROP tablespace IF EXISTS music_tbs;
DROP TABLESPACE
omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
CREATE DATABASE
--创建用户user1并授予user1数据库系统的SYSADMIN权限：
/*
CREATE USER user1 IDENTIFIED BY 'meiriyilian@1234';
ALTER USER user1 SYSADMIN;
*/
omm=# CREATE USER user10 IDENTIFIED BY 'meiriyilian@1234';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# CREATE USER user1 IDENTIFIED BY 'meiriyilian@1234';
ERROR: role "user1" already exists
omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
--使用用户user1连接到数据库musicdb，首先查看当前数据库下有哪些模式；
/*
\q
gsql -d musicdb -U user1 -p 5432 -W meiriyilian@1234 -r
\dn
*/
omm=# \q
omm@modb:~$ gsql -d musicdb -U user1 -p 5432 -W meiriyilian@1234 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
musicdb=> \conninfo You are connected to database "musicdb" as user "user1" via socket in "/tmp" at port "5432".
musicdb=>
\dn
List of schemas
Name | Owner
-----------------+-------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
snapshot | omm
sqladvisor | omm
(10 rows)
2.然后为数据库musicdb创建4个模式，名称自定义
/*
用户user1在数据库musicdb中，创建了4个模式：
CREATE schema schm1 AUTHORIZATION user1;
CREATE schema schm2 AUTHORIZATION user1;
CREATE schema schm3 AUTHORIZATION user1;
CREATE schema schm4 AUTHORIZATION user1;
*/
--查看musicdb数据库下的模式：\dn
--也可以使用sql语句查看模式：
--SELECT catalog_name, schema_name, schema_owner FROM information_schema.schemata;
musicdb=> CREATE schema schm1 AUTHORIZATION user1;
CREATE SCHEMA
musicdb=> CREATE schema schm2 AUTHORIZATION user1;
CREATE SCHEMA
musicdb=> CREATE schema schm3 AUTHORIZATION user1;
CREATE SCHEMA
musicdb=> CREATE schema schm4 AUTHORIZATION user1;
CREATE SCHEMA
musicdb=>
musicdb=> \dn
List of schemas
Name | Owner
-----------------+-------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
schm1 | user1
schm2 | user1
schm3 | user1
schm4 | user1
snapshot | omm
sqladvisor | omm
(14 rows)
musicdb=> SELECT catalog_name, schema_name, schema_owner FROM information_schema.schemata;
catalog_name | schema_name | schema_owner
--------------+--------------------+--------------
musicdb | pg_toast | omm
musicdb | cstore | omm
musicdb | pkg_service | omm
musicdb | dbe_perf | omm
musicdb | snapshot | omm
musicdb | blockchain | omm
musicdb | pg_catalog | omm
musicdb | public | omm
musicdb | sqladvisor | omm
musicdb | dbe_pldebugger | omm
musicdb | dbe_pldeveloper | omm
musicdb | information_schema | omm
musicdb | db4ai | omm
musicdb | schm1 | user1
musicdb | schm2 | user1
musicdb | schm3 | user1
musicdb | schm4 | user1
3.在数据库musicdb的不同的模式下创建同名的表
--在不同模式下，创建相同的表
/*
create table schm1.test07(id integer, comm char(20));
create table schm2.test07(id integer, comm char(20));
create table schm3.test07(id integer, comm char(20));
create table schm4.test07(id integer, comm char(20));
*/
musicdb=> create table schm1.test07(id integer, comm char(20));
CREATE TABLE
musicdb=> create table schm2.test07(id integer, comm char(20));
CREATE TABLE
musicdb=> create table schm3.test07(id integer, comm char(20));
CREATE TABLE
musicdb=> create table schm4.test07(id integer, comm char(20));
CREATE TABLE
--往4个模式中的表test07分别插入一条数据（同一个数据库下，可以直接使用SchemaName.TableName来指定一个表而省略数据库名）：
/*
insert into schm1.test07 values(1, '4 schema schm1');
insert into schm2.test07 values(2, '4 schema schm2');
insert into schm3.test07 values(3, '4 schema schm3');
insert into schm4.test07 values(4, '4 schema schm4');
*/
musicdb=> insert into schm1.test07 values(1, '4 schema schm1');
INSERT 0 1
musicdb=> insert into schm2.test07 values(2, '4 schema schm2');
INSERT 0 1
musicdb=> insert into schm3.test07 values(3, '4 schema schm3');
INSERT 0 1
musicdb=> insert into schm4.test07 values(4, '4 schema schm4');
INSERT 0 1
--执行下面的SQL语句，查看musicdb数据库目前有哪些表
/*
--创建视图：
create or replace view my_tables as
select table_catalog, table_schema, table_name, table_type from information_schema.tables
where table_schema not in ('pg_catalog', 'information_schema','dbe_perf');
--查看视图：
select * from my_tables;
*/
musicdb=> create or replace view my_tables as
musicdb-> select table_catalog, table_schema, table_name, table_type from information_schema.tables
musicdb-> where table_schema not in ('pg_catalog', 'information_schema','dbe_perf');
CREATE VIEW
musicdb=> select * from my_tables;
table_catalog | table_schema | table_name | table_type
---------------+-----------------+------------+------------
musicdb | db4ai | snapshot | BASE TABLE
musicdb | dbe_pldeveloper | gs_errors | BASE TABLE
musicdb | dbe_pldeveloper | gs_source | BASE TABLE
musicdb | public | my_tables | VIEW
musicdb | schm4 | test07 | BASE TABLE
musicdb | schm3 | test07 | BASE TABLE
musicdb | schm2 | test07 | BASE TABLE
musicdb | schm1 | test07 | BASE TABLE
(8 rows)
4.访问musicdb数据库下不同模式的同名表
--musicdb数据库下不同模式的同名表（需要指定模式名前缀）：
/*
select * from schm1.test07;
select * from schm2.test07;
select * from schm3.test07;
select * from schm4.test07;
*/
musicdb=> select * from schm1.test07;
id | comm
----+----------------------
1 | 4 schema schm1
(1 row)
musicdb=> select * from schm2.test07;
id | comm
----+----------------------
2 | 4 schema schm2
(1 row)
musicdb=> select * from schm3.test07;
id | comm
----+----------------------
3 | 4 schema schm3
(1 row)
musicdb=> select * from schm4.test07;
id | comm
----+----------------------
4 | 4 schema schm4
(1 row)
5.实验理解：模式是在数据库层面，用户是在实例层面
--切换进入不同数据库， 发现模式不一样， 而用户在。即用户时跨数据库的，模式是在数据库层面，用户是在实例层面。
/*
--登录musicdb数据库，查看用户和模式
gsql -d musicdb -U user1 -p 5432 -W meiriyilian@1234 -r
\du
\dn
\q
*/
omm@modb:~$ gsql -d musicdb -U user1 -p 5432 -W meiriyilian@1234 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
musicdb=> \du
List of roles
Role name | Attributes
| Member of
-----------+------------------------------------------------------------------------------------------------------------
------+-----------
gaussdb | Sysadmin
| {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin,
UseFT | {}
user1 | Sysadmin
| {}
user3 | Sysadmin
| {}
user10 | Sysadmin
| {}
user2 | Sysadmin
| {}
musicdb=> \dn List of schemas
Name | Owner
-----------------+-------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
schm4 | user1
snapshot | omm
schm1 | user1
schm2 | user1
schm3 | user1
sqladvisor | omm
(14 rows)
\qmusicdb=> \q
omm@modb:~$
/*
--登录omm数据库，查看用户和模式
gsql -r
\du
\dn
\q
*/
omm=# \du
List of roles
Role name | Attributes
| Member of
-----------+------------------------------------------------------------------------------------------------------------
------+-----------
gaussdb | Sysadmin
| {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin,
UseFT | {}
user1 | Sysadmin
| {}
user10 | Sysadmin
| {}
user2 | Sysadmin
| {}
user3 | Sysadmin
| {}
omm=# \dn
List of schemas
Name | Owner
-----------------+--------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
snapshot | omm
sqladvisor | omm
user1 | user1
user10 | user10
user2 | user2
user3 | user3
(14 rows)
omm=# \q
omm@modb:~
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