openGauss每日一练第6天 | 用户连接到某个数据库无法访问其它数据库对象

打卡第六天，心得体会

本节学习获知，用户登录访问某个数据库后，无法在当前所在数据库去访问到其它数据库对象(dblink除外)；

课后作业

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

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=# 
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=>   \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));

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;
 col1 
------
(0 rows)

musicdb1=> select * from musicdb1.public.t11;
 col1 
------
(0 rows)

musicdb1=> 

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.public.t21;
ERROR:  cross-database references are not implemented: "musicdb2.public.t21"
LINE 1: select * from musicdb2.public.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 musicdb2.public.t21;
 col1 
------
(0 rows)

musicdb2=> select * from t21;
 col1 
------
(0 rows)