第6课程schema学习

学习目标

学习openGauss创建模式、修改模式属性和删除模式

模式是一组数据库对象的集合，主要用于控制对数据库对象的访问

1.创建一个名为tpcds的模式

CREATE SCHEMA tpcds;
\dn+ tpcds

omm=# CREATE SCHEMA tpcds;
omm=# \dn+ tpcds
CREATE SCHEMA
                 List of schemas
 Name  | Owner | Access privileges | Description 
-------+-------+-------------------+-------------
 tpcds | omm   |                   | 
(1 row)

2.更改模式owner

创建一个用户tim, 并将tpcds的owner修改为tim，且修改owner前后分别使用\dn+查看模式信息

CREATE USER tim PASSWORD ‘abcd@123’;
\dn+ tpcds;
ALTER SCHEMA tpcds OWNER TO tim;
\dn+ tpcds;

omm=# CREATE USER tim PASSWORD 'abcd@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# \dn+ tpcds;
                 List of schemas
 Name  | Owner | Access privileges | Description 
-------+-------+-------------------+-------------
 tpcds | omm   |                   | 
(1 row)

omm=# ALTER SCHEMA tpcds OWNER TO tim;
ALTER SCHEMA
omm=# \dn+ tpcds;
                 List of schemas
 Name  | Owner | Access privileges | Description 
-------+-------+-------------------+-------------
 tpcds | tim   |                   | 
(1 row)

3.重命名tpcds为tpcds1

ALTER SCHEMA tpcds RENAME TO tpcds1;

omm=# \dn+ tpcds1
                 List of schemas
  Name  | Owner | Access privileges | Description 
--------+-------+-------------------+-------------
 tpcds1 | tim   |                   | 
(1 row)

4.模式中建表

在模式tpcds1中建表customer、插入记录和查询记录
create table tpcds1.customer(id int, name char(30));
insert into tpcds1.customer values(1 ,‘test-schema’);
select * from tpcds1.customer;
\d+ tpcds1.customer;

omm=# create table tpcds1.customer(id int, name char(30));
CREATE TABLE
omm=# insert into tpcds1.customer values(1 ,'test-schema');
INSERT 0 1
omm=# select * from tpcds1.customer;
 id |              name              
----+--------------------------------
  1 | test-schema                   
(1 row)

omm=# \d+ tpcds1.customer;
                          Table "tpcds1.customer"
 Column |     Type      | Modifiers | Storage  | Stats target | Description 
--------+---------------+-----------+----------+--------------+-------------
 id     | integer       |           | plain    |              | 
 name   | character(30) |           | extended |              | 
Has OIDs: no
Options: orientation=row, compression=no

5.删除模式tpcds1

DROP SCHEMA tpcds1;

omm=# DROP SCHEMA tpcds1;
ERROR:  cannot drop schema tpcds1 because other objects depend on it
DETAIL:  table tpcds1.customer depends on schema tpcds1
HINT:  Use DROP ... CASCADE to drop the dependent objects too.
omm=# 

当schema非空时，如果要删除一个schema及其包含的所有对象，需要使用CASCADE关键字

omm=# DROP SCHEMA tpcds1 CASCADE;
NOTICE:  drop cascades to table tpcds1.customer
DROP SCHEMA
omm=# DROP USER tim;
DROP ROLE