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

更多说明：https://www.jianshu.com/p/b2dbc3a0402d

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)

发现更多宝藏

我在喜马拉雅上分享声音

《数据库系统概论(第4版)》，点开链接可以听听，有点意思。

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