(openGauss每日一练第 6天)：openGauss创建模式、修改模式属性和删除模式

1.创建模式

--1、使用gsql登录openGauss
root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 2.0.0 build 78689da9) compiled at 2021-03-31 21:03:52 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=#
-–2、创建名为ds的模式
omm=# CREATE SCHEMA ds;
CREATE SCHEMA

-–3、查看ds模式信息, owner为omm
omm=# \dn+ ds;
                List of schemas
 Name | Owner | Access privileges | Description 
------+-------+-------------------+-------------
 ds   | omm   |                   | 
(1 row)

2.在ds中建表

--1、创建表
omm=# create table ds.t1(id int, name char(30));
CREATE TABLE

--2、插入数据
omm=# insert into ds.t1 values(1 ,'xxxx');
INSERT 0 1

--3、查询验证
omm=# select * from ds.t1;
 id |              name              
----+--------------------------------
  1 | xxxx                          
(1 row)

--4、查看表信息
omm=# \d+ ds.t1;
                               Table "ds.t1"
 Column |     Type      | Modifiers | Storage  | Stats target | Description 
--------+---------------+-----------+----------+--------------+-------------
 id     | integer       |           | plain    |              | 
 name   | character(30) |           | extended |              | 
Has OIDs: no
Options: orientation=row, compression=no

3.修改模式信息

–-1、重命名模式为ds_new
omm=# ALTER SCHEMA ds RENAME TO ds_new;
ALTER SCHEMA

--2、查询模式ds_new下表t1
omm=# select * from ds_new.t1;
 id |              name              
----+--------------------------------
  1 | xxxx                          
(1 row)

--3、创建用户jack 
omm=# CREATE USER jack PASSWORD 'abcd@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE

--4、将ds_new的所有者修改为jack
omm=# ALTER SCHEMA ds_new OWNER TO jack;
ALTER SCHEMA

--5、查询模式ds_new信息
omm=# \dn+ ds_new;
                 List of schemas
  Name  | Owner | Access privileges | Description 
--------+-------+-------------------+-------------
 ds_new | jack  |                   | 
(1 row)

4.删除模式

--删除模式
omm=# DROP SCHEMA ds_new;
ERROR:  cannot drop schema ds_new because other objects depend on it
DETAIL:  table ds_new.t1 depends on schema ds_new
HINT:  Use DROP ... CASCADE to drop the dependent objects too.

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

--1、再次尝试删除模式
omm=# DROP SCHEMA ds_new CASCADE;
NOTICE:  drop cascades to table ds_new.t1
DROP SCHEMA

--2、删除用户
omm=# DROP USER jack;
DROP ROLE

练习：

1.创建一个名为tpcds的模式

omm=# create schema tpcds;
CREATE SCHEMA

omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 

 snapshot    | omm   |                   | snapshot schema
 tpcds       | omm   |                   | 
(6 rows)

2.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

omm=# create user tim identified by 'tim_1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE

omm=# \du+
                                                                     List of roles
 Role name |                                                    Attributes                                         


           | Member of | Description 
-----------+-------------------------------------------------------------------------------------------------------
-----------+-----------+-------------
 gaussdb   | Sysadmin                                                                                              
           | {}        | 
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyad
min, UseFT | {}        | 
 tim       |                                                                                                       
           | {}        | 

omm=# alter schema tpcds owner to tim;
ALTER SCHEMA

omm-# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
 tim         | tim   |                   | 
 tpcds       | tim   |                   | 
(7 rows)

3.重命名tpcds为tpcds1

omm=# alter schema tpcds rename to tpcds2;
ALTER SCHEMA

omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
 tim         | tim   |                   | 
 tpcds2      | tim   |                   | 
(7 rows)

4.在模式tpcds1中建表customer、插入记录和查询记录

omm=# create table tpcds2.customer(id number(10), name varchar(50));
CREATE TABLE

omm=# insert into tpcds2.customer values(1,'xiaoming');
INSERT 0 1

omm=# select * from tpcds2.customer;
 id |   name   
----+----------
  1 | xiaoming
(1 row)

5.删除模式tpcds1

omm=# drop schema tpcds2 cascade;
NOTICE:  drop cascades to table tpcds2.customer
DROP SCHEMA
omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
 tim         | tim   |                   | 
(6 rows)

6.删除用户

omm=# drop user tim;
DROP ROLE

omm=# \du+
                                                                     List of roles
 Role name |                                                    Attributes                                         
           | Member of | Description 
-----------+-------------------------------------------------------------------------------------------------------
-----------+-----------+-------------
 gaussdb   | Sysadmin                                                                                              
           | {}        | 
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyad
min, UseFT | {}        |