Postgres database basic operations

1. Link to the database

• Order

/# PGPASSWORD=liubei@161 psql -U liubei  -d xishu

Of course, you can also enter the password interactively

psql -U liubei  -d xishu

• output

psql (13.8 (Debian 13.8-1.pgdg110+1))
Type "help" for help.

xishu=#

2. Library operation

2.1 Create library

xishu=# create database jing_zhou;
CREATE DATABASE

2.2 View database

• Order

xishu=# \l

• output

                              List of databases
   Name    | Owner  | Encoding |  Collate   |   Ctype    | Access privileges
-----------+--------+----------+------------+------------+-------------------
 jing_zhou | liubei | UTF8     | en_US.utf8 | en_US.utf8 |
 postgres  | liubei | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | liubei | UTF8     | en_US.utf8 | en_US.utf8 | =c/liubei        +
           |        |          |            |            | liubei=CTc/liubei
 template1 | liubei | UTF8     | en_US.utf8 | en_US.utf8 | =c/liubei        +
           |        |          |            |            | liubei=CTc/liubei
 xishu     | liubei | UTF8     | en_US.utf8 | en_US.utf8 |
(5 rows)

The database we created can be seen abovejing_zhou

2.3 Switch database

• Order

xishu=# \c jing_zhou;

• output

You are now connected to database "jing_zhou" as user "liubei".

2.4 Modify the library name

xishu=# alter database jing_zhou rename to new_jing_zhou;

2.5 Delete the database

xishu=# drop database new_jing_zhou;

3. Table operation

3.1 Create table

• Order

CREATE TABLE users(
   ID INT PRIMARY KEY     NOT NULL,
   name           CHAR(50)    NOT NULL,
   mail        CHAR(50),
   phone        CHAR(50)
);

3.2 view table list

• Order

xishu=# \d

• output

         List of relations
 Schema |  Name   | Type  | Owner
--------+---------+-------+--------
 public | users   | table | liubei
(2 rows)

3.3 Delete table

xishu=# drop table users;

4. Data manipulation

4.1 Insert data

INSERT INTO users (ID,name,mail)  
VALUES (1,'guanYu','[email protected]');

4.2 Query data

xishu=# select * from users;

• output

 id |                        name                        |                        mail                        | phone
----+----------------------------------------------------+----------------------------------------------------+-------
  1 | guanYu                                             | guanyu@xishu.com                                   |

4.3 Delete data

delete from users where name='guanYu';

5. Users & Permissions

• CREATE USERand REATE ROLEthe difference
  • CREATE USER:defaultLOGIN
  • CREATE ROLE:defaultNOLOGIN

5.1 Create user

• Create user and add password

CREATE USER guanyu PASSWORD 'guanyu@123456';

or

CREATE ROLE guanyunchang LOGIN PASSWORD 'guanyu@123456';

• Create an admin user

CREATE USER kongming SUPERUSER PASSWORD 'kongming@123456';

• Create a user who can create databases

CREATE USER pangtong CREATEDB;

• Create a user who can create tables

CREATE USER pangtong CREATETABLE;

• Create a user that can create users

CREATE USER fazheng CREATEROLE;

5.2 View users

• Order

SELECT * FROM pg_roles;

• output

          rolname          | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolconnlimit | rolpassword | rolvaliduntil | rolbypassrls | rolconfig |  oid
---------------------------+----------+------------+---------------+-------------+-------------+----------------+--------------+-------------+---------------+--------------+-----------+-------
 pg_signal_backend         | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  4200
 pg_read_server_files      | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  4569
 guanyu                    | f        | t          | f             | f           | t           | f              |           -1 | ********    |               | f            |           | 16403
 liubei                    | t        | t          | t             | t           | t           | t              |           -1 | ********    |               | t            |           |    10
 pg_write_server_files     | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  4570
 pg_execute_server_program | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  4571
 fazheng                   | f        | t          | t             | f           | t           | f              |           -1 | ********    |               | f            |           | 16406
 pg_read_all_stats         | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  3375
 pg_monitor                | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  3373
 guanyunchang              | f        | t          | f             | f           | t           | f              |           -1 | ********    |               | f            |           | 16407
 pangtong                  | f        | t          | f             | t           | t           | f              |           -1 | ********    |               | f            |           | 16405
 pg_read_all_settings      | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  3374
 pg_stat_scan_tables       | f        | t          | f             | f           | f           | f              |           -1 | ********    |               | f            |           |  3377
 kongming                  | t        | t          | f             | f           | t           | f              |           -1 | ********    |               | f            |           | 16404
(14 rows)

5.3 Delete user

drop user guanyunchang ;

5.4 Modify user name

• Order

ALTER USER guanyu RENAME TO guanyunchang;

• output

NOTICE:  MD5 password cleared because of role rename
ALTER ROLE

As can be seen above, the password is cleared.

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5.5 Change password

• Order

ALTER USER guanyunchang PASSWORD 'guanyunchang@123456';

5.6 Permission recovery

I won’t expand and write here, it can correspond to the permissions when creating users

 ALTER ROLE fazheng NOCREATEDB ;

6. User table permissions

SELECT、INSERT、UPDATE、DELETE、TRUNCATE、REFERENCES、TRIGGER、CREATE、CONNECT、TEMPORARY、EXECUTE、USAGE

6.1 Add table permissions for users

• Add user table permissions

Give user Guan Yunchang permission to modify the user table

GRANT UPDATE ON users TO guanyunchang;

• View permissions for all users

Give all users permission to view the users table

 GRANT SELECT ON users TO PUBLIC;

• Give the user all permissions

Grant all permissions to the user Guan Yunchang user table

GRANT ALL ON users TO guanyunchang;

6.2 Reclaim User Table Permissions

REVOKE DELETE ON users FROM guanyunchang ;

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