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第6天| openGauss中用户一次只能连接到一个数据库，没法访问其他数据库的对象

news 2025/7/18 6:49:26

接着昨天继续学习openGauss,今天是第6天了。今天学习内容是使用一个用户访问多个数据库。
老规矩，先登陆墨天轮为我准备的实训实验室，并创建好表空间

root@modb:~# su - omm
omm@modb:~$ gsql -r
CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';

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

omm=# CREATE DATABASE musicdb1 WITH TABLESPACE = music_tbs;
CREATE DATABASE
omm=# CREATE DATABASE musicdb2 WITH TABLESPACE = music_tbs;
CREATE DATABASE

接着创建用户并赋予权限

omm=# CREATE USER user1 IDENTIFIED BY 'user1@1234';
omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE

–用户user1登录到数据库musicdb1，创建表t11，并插入、查看数据

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=>  select * from t11;
(1 row)musicdb1=>          col1         
----------------------Hello openGauss! 11

–用户user1登录到数据库musicdb2，创建表t21，并插入、查看数据

omm=#  \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');
INSERT 0 1
musicdb1=>  select * from t21;
(1 row)musicdb1=>          col1         
----------------------Hello openGauss! 21

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
musicdb1=> select * from musicdb1.public.t11;col1         
----------------------Hello openGauss! 11 
(1 row)

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;

执行玩命令后可以看见报错了

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         
----------------------Hello openGauss! 21 
(1 row)

切换到musicdb2 访问t21成功。