openGauss每日一练第11天 |openGauss逻辑结构：数据库管理

1.创建表空间enmtbs和数据库musicdb

omm=# create tablespace enmtbs relative location 'tablespace/enmtbs';
CREATE TABLESPACE
omm=# create database musicdb tablespace enmtbs ;
CREATE DATABASE

2.查看数据库集簇中有哪些数据库

omm=# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------
 musicdb   | omm   | UTF8     | C       | C     | 
 omm       | omm   | UTF8     | C       | C     | 
 postgres  | omm   | UTF8     | C       | C     | 
 template0 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
 template1 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
(5 rows)omm=# select datname from pg_database ;
  datname  
-----------
 template1
 omm
 template0
 musicdb
 postgres
(5 rows)

3.查看数据库默认的表空间信息

omm=# select spcname from pg_tablespace where oid = ( select dattablespace from pg_database where datname = 'musicdb' );
 spcname 
---------
 enmtbs
(1 row)

4.查看数据库下有哪些模式

omm=# \dn+
                                         List of schemas
      Name       | Owner | Access privileges |           Description            | WithBlockChain 
-----------------+-------+-------------------+----------------------------------+----------------
 blockchain      | omm   |                   | blockchain schema                | f
 cstore          | omm   |                   | reserved schema for DELTA tables | f
 db4ai           | omm   | omm=UC/omm       +| db4ai schema                     | f
                 |       | =U/omm            |                                  | 
 dbe_perf        | omm   |                   | dbe_perf schema                  | f
 dbe_pldebugger  | omm   | omm=UC/omm       +| dbe_pldebugger schema            | f
                 |       | =U/omm            |                                  | 
 dbe_pldeveloper | omm   | omm=UC/omm       +| dbe_pldeveloper schema           | f
                 |       | =U/omm            |                                  | 
 pkg_service     | omm   |                   | pkg_service schema               | f
 public          | omm   | omm=UC/omm       +| standard public schema           | f
                 |       | =U/omm            |                                  | 
 snapshot        | omm   |                   | snapshot schema                  | f
 sqladvisor      | omm   | omm=UC/omm       +| sqladvisor schema                | f
                 |       | =U/omm            |                                  | 
(10 rows)

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
(10 rows)

5.查询当前连接的数据库下有哪些表：

omm=# with my_tables(table_catalog, table_schema, table_name, table_type) as
omm-#       (   select table_catalog, table_schema, table_name, table_type
omm(#           from information_schema.tables
omm(#          where table_schema not in ('pg_catalog', 'information_schema','dbe_perf')
omm(#        )
omm-# 
omm-#  select * from my_tables;
 omm           | db4ai           | snapshot   | BASE TABLE
 omm           | dbe_pldeveloper | gs_errors  | BASE TABLE
 omm           | dbe_pldeveloper | gs_source  | BASE TABLE

6.更改数据库默认的表空间

omm=# create tablespace new_tbs relative location 'tablespace/new_tbs';
CREATE TABLESPACE
omm=# alter database musicdb set tablespace new_tbs ;
ALTER DATABASE## 检查数据库默认空间是否发生更改omm=# select spcname from pg_tablespace where oid = ( select dattablespace from pg_database where datname = 'musicdb' );
 new_tbs

7.重新命名数据库

omm=# alter database musicdb rename to musicdb_new;
ALTER DATABASEomm=# \l
 musicdb_new | omm   | UTF8     | C       | C     | 
 omm         | omm   | UTF8     | C       | C     | 
 postgres    | omm   | UTF8     | C       | C     | 
 template0   | omm   | UTF8     | C       | C     | =c/omm           +
             |       |          |         |       | omm=CTc/omm
 template1   | omm   | UTF8     | C       | C     | =c/omm           +
             |       |          |         |       | omm=CTc/omm

8.修改数据库的默认用户

omm=# create user user1 sysadmin identified by 'abcd@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# alter database musicdb_new owner to user1 ;
ALTER DATABASEomm=# \l
 musicdb_new | user1 | UTF8     | C       | C     | 
 omm         | omm   | UTF8     | C       | C     | 
 postgres    | omm   | UTF8     | C       | C     | 
 template0   | omm   | UTF8     | C       | C     | =c/omm           +
             |       |          |         |       | omm=CTc/omm
 template1   | omm   | UTF8     | C       | C     | =c/omm           +
             |       |          |         |       | omm=CTc/omm

9.删除数据库

omm=# drop database musicdb_new ;
DROP DATABASE