openGauss每日一练第6天-一次只能连接一个库

1.创建用户user1，分别在数据库musicdb1、数据库musicdb2创建表t11,t21

omm=# 
omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb1  WITH TABLESPACE = music_tbs;
CREATE DATABASE
omm=# CREATE DATABASE musicdb2  WITH TABLESPACE = music_tbs;
CREATE DATABASE
omm=# CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
omm=# \c musicdb1 user1
Password for user user1: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb1" as user "user1".
musicdb1=> create table t11(col1 char(20));
CREATE TABLE
musicdb1=>  insert into t11 values('Hello openGauss! 11');
INSERT 0 1
musicdb1=> \c musicdb2 user1      
Invalid command \cdb2. Try \? for help.
musicdb1=> \c musicdb2 user1
Password for user user1: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user1".
musicdb2=> create table t21(col1 char(20));
CREATE TABLE
musicdb2=>  insert into t21 values('Hello openGauss! 21');
musicdb2=> INSERT 0 1

2.user1用户连接到数据库musicdb1，并访问数据库musicdb1下的表t11

musicdb2=> \c musicdb1 user1
Password for user user1: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb1" as user "user1".
musicdb1=> select * from t11;
(1 row)

musicdb1=>          col1         
----------------------
 Hello openGauss! 11 

3.在这个连接中（使用数据库用户user1连接到数据库musicdb1）访问数据库musicdb2下的t21表(会报错)

musicdb1=> select * from musicdb2.t21;
ERROR:  schema "musicdb2" does not exist
LINE 1: select * from musicdb2.t21;
                      ^
musicdb1=> select * from t21;
ERROR:  relation "t21" does not exist on gaussdb
LINE 1: select * from t21;

4.使用数据库用户user1连接到数据库musicdb2，访问数据库musicdb2下的t21表。

musicdb1=> \c musicdb2 user1
Password for user user1: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user1".
musicdb2=> select * from t21musicdb2-> ;

musicdb2=>          col1         
----------------------
 Hello openGauss! 21 
(1 row)