第 23 课 PostgreSQL 创建自己的数据库、模式、用户

1. 修改PostgreSQL数据库默认用户postgres的密码
[root@izwz90tx4egvh4qj3p95vsz ~]# sudo -u postgres psql
psql (10.4)
Type "help" for help.

postgres=# ALTER USER postgres WITH PASSWORD 'duyeweb';
ALTER ROLE

注意：

密码postgres要用引号引起来
命令最后有分号

2. 修改linux系统postgres用户的密码
步骤一：删除用户postgres的密码
[root@izwz90tx4egvh4qj3p95vsz ~]# sudo passwd -d postgres
Removing password for user postgres.
passwd: Success

步骤二：设置用户postgres的密码
[root@izwz90tx4egvh4qj3p95vsz ~]# sudo -u postgres passwd
Changing password for user postgres.
New password:
BAD PASSWORD: The password fails the dictionary check - it does not contain enough DIFFERENT characters
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

3. 使用超级用户postgres创建新数据库和用户

创建数据库duyeweb

[root@izwz90tx4egvh4qj3p95vsz ~]# sudo -u postgres psql
could not change directory to "/root": Permission denied
psql (10.4)
Type "help" for help.

postgres=# create database duyeweb;
CREATE DATABASE
postgres=# \l
                                  List of databases
   Name    | Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
duyeweb   | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
postgres | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =Tc/postgres         +
           |          |          |             |             | postgres=CTc/postgres+
           |          |          |             |             | duye=C/postgres
template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres

创建新用户duye
设置密码'123456'
赋予登录和创建数据库对象的权限

[root@izwz90tx4egvh4qj3p95vsz ~]# sudo -u postgres psql
could not change directory to "/root": Permission denied
psql (10.4)
Type "help" for help.

postgres=# create user duye;
CREATE ROLE
postgres=# alter user duye password '123456';
ALTER ROLE
postgres=# \du
                                   List of roles
Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
duye      |                                                            | {}
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

postgres=# alter user duye createrole createdb replication login;
ALTER ROLE
postgres=# \du
                                   List of roles
Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
duye      | Create role, Create DB, Replication                        | {}
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

修改客户端认证方式：vim /var/lib/pgsql/10/data/pg_hba.conf

修改用户的认证方式为md5：

# "local" is for Unix domain socket connections only
local   all             all                                     md5
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             127.0.0.1/32            ident
host    replication     all             ::1/128                 ident

重新加载配置：

systemctl reload postgresql-10

使用新用户duye登录新的数据库duyeweb

[root@izwz90tx4egvh4qj3p95vsz ~]# psql duyeweb -Uduye -W
Password for user duye:
psql (10.4)
Type "help" for help.

duyeweb=# \l
                                  List of databases
   Name    | Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
duyeweb   | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
postgres | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =Tc/postgres         +
           |          |          |             |             | postgres=CTc/postgres+
           |          |          |             |             | duye=C/postgres
template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
(4 rows)

duyeweb=# \du
                                   List of roles
Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
duye      | Superuser, Create role, Create DB, Replication             | {}
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

duyeweb=#

4. 创建模式
schema是逻辑别构，将数据库进行逻辑划分。同一数据库下可以有多个schema，不同数据库下的schema互不相关。
查看模式
duyeweb=# select current_schema;
current_schema
----------------
public
(1 row)
duyeweb=# show search_path
   search_path
-----------------
"$user", public
(1 row)
duyeweb=# \dn
List of schemas
Name | Owner
--------+----------
public | postgres
(1 row)

duyeweb=# select * from pg_catalog.pg_namespace order by 1;
      nspname       | nspowner |               nspacl
--------------------+----------+-------------------------------------
information_schema |       10 | {postgres=UC/postgres,=U/postgres}
pg_catalog         |       10 | {postgres=UC/postgres,=U/postgres}
pg_temp_1          |       10 |
pg_toast           |       10 |
pg_toast_temp_1    |       10 |
public             |       10 | {postgres=UC/postgres,=UC/postgres}
(6 rows)

创建一个模式
duyeweb=# \h create schema
Command:     CREATE SCHEMA
Description: define a new schema
Syntax:
CREATE SCHEMA schema_name [ AUTHORIZATION role_specification ] [ schema_element [ ... ] ]
CREATE SCHEMA AUTHORIZATION role_specification [ schema_element [ ... ] ]
CREATE SCHEMA IF NOT EXISTS schema_name [ AUTHORIZATION role_specification ]
CREATE SCHEMA IF NOT EXISTS AUTHORIZATION role_specification

where role_specification can be:

    user_name
| CURRENT_USER
| SESSION_USER
duyeweb=# CREATE SCHEMA IF NOT EXISTS duyeweb;
CREATE SCHEMA
duyeweb=# \dn
List of schemas
Name   | Owner
---------+----------
duyeweb | duye
public | postgres
(2 rows)