openGauss每日一练第4天 | 多用户访问同个数据库

打卡第四天，多用户访问同个数据库

今天学联一个数据库可以被多个用户访问。这个感觉应该是每个数据库都应该具备的。

openGauss创建用户的同时，会创建一个角色和schema,但schema不同于oracle，schema不一定是一个用户。

创建用户：

    CREATE USER 用户名 IDENTIFIED BY '密码';

授予用户sysadmin,类似oracle dba权限：

    ALTER USER 用户名 SYSADMIN;

\du或\dg 查看用户或角色

\dn 查看schema

gsql切换登录数据库或用户：

    \c 数据库名 用户名 (如不想切换数据库，只切换用户 \c - 用户名)

\dt 查看数据库表信息

课后作业

1.创建用户user1、user2、user3，授予user1、user2、user3数据库系统的SYSADMIN权限：

musicdb=#  CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
musicdb=#  CREATE USER user2 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
musicdb=#  CREATE USER user3 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
musicdb=# ALTER USER user1 SYSADMIN;
ALTER ROLE
musicdb=# ALTER USER user2 SYSADMIN;
ALTER ROLE
musicdb=# ALTER USER user3 SYSADMIN;
ALTER ROLE
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2.分别使用user1、user2、user3访问数据库musicdb2，创建各自的表，并插入数据。表名和数据如下：

表名分别为： products1、 products2、 products3

向表中插入数据：

musicdb=# \c - user1
Password for user user1: 
musicdb=> Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user1".

musicdb=>   create table products1(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb=> insert into products1(product_id,product_name,category) values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb=> \c - user2
Password for user user2: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user2".
musicdb=>   create table products2(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb=> 
musicdb=> insert into products2(product_id,product_name,category) values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb=> \c - user3
Password for user user3: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user3".
musicdb=>   create table products3(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb=> insert into products3(product_id,product_name,category) values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb=> 
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3.使用user1、user2、user3用户中的任何一个，查看当前数据库musicdb2有哪些表；

musicdb=> \dt
                           List of relations
 Schema |   Name    | Type  | Owner |             Storage              
--------+-----------+-------+-------+----------------------------------
 user1  | products1 | table | user1 | {orientation=row,compression=no}
(1 row)
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