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PostgreSQL使用

news 来源：原创 2025/6/9 22:33:48

一、PostgreSQL语法
PostgreSQL表、模式、库三者之间的关系
库 -> 模式 -> 表、视图、函数等等对象。

在postgresql的交互式终端psql中，“\”开头的命令称为元命令（类似mysql的show语句），用于快速管理数据库。
常见元命令：
   \1   列出所有数据库
   \c   [数据库名] 或 \connect [数据库名]
   \dn   列出所有模式（Schema）
   \?    显示pgsql命令的说明（元命令查询帮助）
   \q   退出psql
   \dt   列出当前数据库的所有表
   \d [TABLE] 查看表结构
   \du   列出所有用户

库和表相关命令
1.列出库
   方法一：\l
   方法二：\l+
   方法三：select datname from pg_database;
   # pg_database是系统表，存储了PostgreSQL实例中所有数据库的元信息（如数据库名称、所有者、编码等）。属于系统目录（system catalog）：类似mysql的information_schema，但postgresql的系统目录更底层且直接存储在pg_catalog模式中。

# pg_database是系统目录表，所以无论当前连接到哪个数据库，该表始终可见，系统表默认属于pg_catalog模式，而pg_catalog始终位于搜索路径(search_path)的首位。因此，查询时无需显式指定模式(如 pg_catalog.pg_database)

2.创建库
create database 库名;

3.删除库
drop database 库名;

4.切换库
\c 库名;

5.查看库大小
   方法一：以字节为单位返回数据库的大小
   select pg_database_size('库名')；
   方法二：人性化返回数据库的大小（带k、m等等）
   select pg_size_pretty(pg_database_size('库名'));

6.列出表
\dt; (显示search_path中模式里的表，默认public。)

\d （列出表，视图和序列。）

\d+ （列出表，视图和序列。）

\dt my_schema.* （列出指定模式下的表（例如 my_schema)）

\dt *.* （查看当前数据库的所有表（包括系统表））

select * from pg_tables where schemaname='public'; （使用sql方式列出当前数据库中public模式下的所有表及其详细信息。）

7.创建表
create table tablename(字段1 类型，字段2 类型，… 字段n 类型);

8.复制表
create table new_table as table table_name;

9.删除表
drop table 表名;

10.查看表结构
\d 表名;

11.在指定模式中创建表
create table 模式名.表名(字段1 类型，字段2 类型，… 字段n 类型);

模式操作命令
1.创建模式
create schema 模式名;

2.显示搜索路径
show search_path;

3.删除模式
drop schema 模式名;

4.查看所有模式
   \dn

   select 列名 from 模式名.表名;
   select schema_name from information_shcema.schemata;
   schema_name是列名 information_schema是模式名 shcemata是表名

5.切换当前模式
切换到单个schema
set search_path to new_schema;

切换到多个schema（按优先级排序）
set search_path to 模式名1，模式名2;

6.查看当前所在schema
select current_schema();

7.查看搜索路径（search path）
show search_path;

数据操作相关
1.添加数据
insert into tablename values(value1,value2,…valuen);

2.查询数据
select * from tablename;

3.修改数据
update tablename set 字段=值 where 条件;

4.删除数据
delete from tablename where 条件;

PostgreSQL的三种备份方式
   1.SQL转储
   2.文件系统级备份
   3.连续归档
SQL转储最常用

备份语法，使用pg_dump命令。（一次备份一个库。）
pg_dump dbname > dumpfile

pg_dump -h host1 dbname | psql -h host2 dbname # 从主机1转储到主机2

恢复语法，使用psql命令。
psql dbname < dumpfile

psql --set ON_ERROR_STOP=om dbname < infile # 遇到错误退出。

备份给定数据库集簇中的全部内容，使用pg_dumpall命令。

备份语法
pg_dumpall > dumpfile
恢复语法
psql -f dumpfile postgres

杂七杂八
配置密码
alter user username with password 'password';
远程连接
psql -h remoteip

二、PostgreSQL示例

列出库
postgres=# \lList of databasesName    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | LocaleProvider |   Access privileges   
-----------+----------+----------+-------------+-------------+------------+-------
----------+-----------------------postgres  | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  | template0 | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  | =c/postgres          +|          |          |             |             |            |       | postgres=CTc/postgrestemplate1 | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  | =c/postgres          +|          |          |             |             |            |       | postgres=CTc/postgres
(3 rows)postgres=# \l+List of databasesName    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | LocaleProvider |   Access privileges   |  Size   | Tablespace |                Descript
ion                 
-----------+----------+----------+-------------+-------------+------------+-------
----------+-----------------------+---------+------------+------------------------
--------------------postgres  | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  |                       | 7229 kB | pg_default | default administrative 
connection databasetemplate0 | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  | =c/postgres          +| 7073 kB | pg_default | unmodifiable empty data
base|          |          |             |             |            |       | postgres=CTc/postgres |         |            | template1 | postgres | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 |            | libc  | =c/postgres          +| 7153 kB | pg_default | default template for ne
w databases|          |          |             |             |            |       | postgres=CTc/postgres |         |            | 
(3 rows)postgres=# select datname from pg_database;datname  
-----------postgrestemplate1template0
(3 rows)创建、删除、切换库
postgres=# create database mydb;
CREATE DATABASE
postgres=# drop database mydb;
DROP DATABASE
postgres=# \c mydb
connection to server on socket "/tmp/.s.PGSQL.5432" failed: FATAL:  database "mydb" does not exist
Previous connection kept
postgres=# create database mydb;
CREATE DATABASE
postgres=# \c mydb
You are now connected to database "mydb" as user "postgres".查看库大小
mydb=# select pg_database_size('mydb');pg_database_size 
------------------7484207
(1 row)mydb=# select pg_size_pretty(pg_database_size('mydb'));pg_size_pretty 
----------------7309 kB
(1 row)列出表
mydb=# create table aaa (id int,name varchar);
CREATE TABLE
mydb=# \dt;List of relationsSchema | Name | Type  |  Owner   
--------+------+-------+----------public | aaa  | table | postgres
(1 row)mydb=# \dList of relationsSchema | Name | Type  |  Owner   
--------+------+-------+----------public | aaa  | table | postgres
(1 row)mydb=# \d+List of relationsSchema | Name | Type  |  Owner   | Persistence | Access method |    Size    | Des
cription 
--------+------+-------+----------+-------------+---------------+------------+----
---------public | aaa  | table | postgres | permanent   | heap          | 8192 bytes | 
(1 row)mydb=# dt my_schema.*
mydb-# ;
ERROR:  syntax error at or near "dt"
LINE 1: dt my_schema.*^
mydb=# dt *.*
mydb-# ;
ERROR:  syntax error at or near "dt"
LINE 1: dt *.*^
mydb=# \dt *.*;List of relationsSchema       |           Name           |    Type     |  Owner   
--------------------+--------------------------+-------------+----------information_schema | sql_features             | table       | postgresinformation_schema | sql_implementation_info  | table       | postgresinformation_schema | sql_parts                | table       | postgresinformation_schema | sql_sizing               | table       | postgrespg_catalog         | pg_aggregate             | table       | postgrespg_catalog         | pg_am                    | table       | postgrespg_catalog         | pg_amop                  | table       | postgrespg_catalog         | pg_amproc                | table       | postgrespg_catalog         | pg_attrdef               | table       | postgrespg_catalog         | pg_attribute             | table       | postgrespg_catalog         | pg_auth_members          | table       | postgrespg_catalog         | pg_authid                | table       | postgrespg_catalog         | pg_cast                  | table       | postgrespg_catalog         | pg_class                 | table       | postgrespg_catalog         | pg_collation             | table       | postgrespg_catalog         | pg_constraint            | table       | postgrespg_catalog         | pg_conversion            | table       | postgrespg_catalog         | pg_database              | table       | postgrespg_catalog         | pg_db_role_setting       | table       | postgrespg_catalog         | pg_default_acl           | table       | postgrespg_catalog         | pg_depend                | table       | postgrespg_catalog         | pg_description           | table       | postgrespg_catalog         | pg_enum                  | table       | postgrespg_catalog         | pg_event_trigger         | table       | postgrespg_catalog         | pg_extension             | table       | postgrespg_catalog         | pg_foreign_data_wrapper  | table       | postgrespg_catalog         | pg_foreign_server        | table       | postgrespg_catalog         | pg_foreign_table         | table       | postgrespg_catalog         | pg_index                 | table       | postgrespg_catalog         | pg_inherits              | table       | postgrespg_catalog         | pg_init_privs            | table       | postgrespg_catalog         | pg_language              | table       | postgrespg_catalog         | pg_largeobject           | table       | postgrespg_catalog         | pg_largeobject_metadata  | table       | postgrespg_catalog         | pg_namespace             | table       | postgres
mydb=# \dt my_schema.*;
Did not find any relation named "my_schema.*".
mydb=# select * from pg_tables where schemaname='public';schemaname | tablename | tableowner | tablespace | hasindexes | hasrules | hastri
ggers | rowsecurity 
------------+-----------+------------+------------+------------+----------+-------
------+-------------public     | aaa       | postgres   |            | f          | f        | f     | f
(1 row)创建表
mydb=# create table test(id int,name char(10),age int);
CREATE TABLE
mydb=# create table test2 as table test;
SELECT 0
mydb=# \dt;List of relationsSchema | Name  | Type  |  Owner   
--------+-------+-------+----------public | aaa   | table | postgrespublic | test  | table | postgrespublic | test2 | table | postgres
(3 rows)删除表
mydb=# drop table test2;
DROP TABLE
mydb=# \dt;List of relationsSchema | Name | Type  |  Owner   
--------+------+-------+----------public | aaa  | table | postgrespublic | test | table | postgres
(2 rows)查看表结构
mydb=# \d test;Table "public.test"Column |     Type      | Collation | Nullable | Default 
--------+---------------+-----------+----------+---------id     | integer       |           |          | name   | character(10) |           |          | age    | integer       |           |          | 创建模式
mydb=# \c postgres;
You are now connected to database "postgres" as user "postgres".
postgres=# create schema hr;
CREATE SCHEMA查看默认模式
postgres=# show search_path;search_path   
-----------------"$user", public
(1 row)删除模式、查看所有模式
postgres=# drop schema hr;;
DROP SCHEMA
postgres=# drop schema hr cascade;
ERROR:  schema "hr" does not exist
postgres=# create schema hr;
CREATE SCHEMA
postgres=# drop schema hr cascade;
DROP SCHEMA
postgres=# \dn;List of schemasName  |       Owner       
--------+-------------------public | pg_database_owner
(1 row)postgres=# select schema_name from information_schema.schemata;schema_name     
--------------------information_schemapg_catalogpg_toastpublic
(4 rows)在指定模式中创建表、查看当前模式、查看当前所在shcema、查看搜索路径
postgres=# create schema hr;
CREATE SCHEMA
postgres=# create table hr.employees (id serial primary key,name text);
CREATE TABLE
postgres=# set search_path to hr;
SET
postgres=# set search_path to hr,public;
SET
postgres=# select current_schema();current_schema 
----------------hr
(1 row)postgres=# show search_path;search_path 
-------------hr, public
(1 row)PostgreSQL模式隔离性
postgres=# create database mydb;  # 创建数据库test
ERROR:  database "mydb" already exists
postgres=# \c mydb  # 使用test库。
You are now connected to database "mydb" as user "postgres".
mydb=# create schema schema1; # 创建模式1.
CREATE SCHEMA
mydb=# create schema schema2; # 创建模式2.
CREATE SCHEMA
mydb=# create table shcema1.users (id int);
ERROR:  schema "shcema1" does not exist
LINE 1: create table shcema1.users (id int);^
mydb=# create table schema1.users (id int);  # 在模式1创建users表
CREATE TABLE
mydb=# insert into schema1.users values(1);  # 向模式1的users表插入数据1.
INSERT 0 1
mydb=# create table schema2.users (id int);  # 在模式2创建users表
CREATE TABLE
mydb=# insert into schema2.users values(2);  # 向模式2的users表插入数据2.
INSERT 0 1
mydb=# select * from schema1.users;  # 显式指定模式名来查询模式1的users表数据。id 
----1
(1 row)mydb=# select * from schema2.users; # 显式指定模式名来查询模式2的users表数据。id 
----2
(1 row)mydb=# set search_path to schema1;  # 设置搜索路径为模式1，查询时无需显式指定模式名。
SET
mydb=# select * from users;id 
----1
(1 row)mydb=# set search_path to schema2; # 设置搜索路径为模式2，查询时无需显式指定模式名。
SET
mydb=# select * from users;id 
----2
(1 row)数据操作相关
postgres=# create table test(id int,name char(10),age int);
CREATE TABLE
postgres=# insert into test values(1,'zhangsan',18);
INSERT 0 1
postgres=# select * from test;id |    name    | age 
----+------------+-----1 | zhangsan   |  18
(1 row)postgres=# update test set age=20 where id=1;
UPDATE 1
postgres=# select * from test;id |    name    | age 
----+------------+-----1 | zhangsan   |  20
(1 row)postgres=# delete from test where id=1;
DELETE 1
postgres=# select * from test;id | name | age 
----+------+-----
(0 rows)备份相关sql转储单个库及恢复
转储
postgres=# create database my_db; 
CREATE DATABASE
postgres=# \c my_db
You are now connected to database "my_db" as user "postgres".
my_db=# create schema s1;
CREATE SCHEMA
my_db=# create schema s2;
CREATE SCHEMA
my_db=# create table s1.a(id int)
my_db-# ;
CREATE TABLE
my_db=# create table s2.a(id int);
CREATE TABLE
my_db=# insert into s1.a values(1);
INSERT 0 1
my_db=# insert into s2.a values(2);
INSERT 0 1
my_db=# select  * from s1.a;id 
----1
(1 row)my_db=# select * from s2.a;id 
----2
(1 row)my_db=# exit;
[postgres@localhost ~]$ pg_dump my_db > aaa  # 备份my_db库到aaa文件中
[postgres@localhost ~]$ ls
aaa  logfile 
[postgres@localhost ~]$ cat aaa  # 查看备份信息
--
-- PostgreSQL database dump
---- Dumped from database version 15.4
-- Dumped by pg_dump version 15.4SET statement_timeout = 0;
SET lock_timeout = 0;
…略
通过查看备份文件内的信息，发现这是该文件内容是由一些sql命令组合而成的。恢复
postgres=# drop database my_db;
DROP DATABASE[postgres@localhost ~]$ psql my_db < aaa
psql: error: connection to server on socket "/tmp/.s.PGSQL.5432" failed: FATAL:  database "my_db" does not existpostgres=# create database my_db;
CREATE DATABASEpostgres=# exit[postgres@localhost ~]$ psql my_db < aaa
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
CREATE SCHEMA
ALTER SCHEMA
CREATE SCHEMA
ALTER SCHEMA
SET
SET
CREATE TABLE
ALTER TABLE
CREATE TABLE
ALTER TABLE
COPY 1
COPY 1[postgres@localhost ~]$ psql
psql (15.4)
Type "help" for help.postgres=# \c my_db
You are now connected to database "my_db" as user "postgres".my_db=# \dt
Did not find any relations.my_db=# select * from s1.a;id 
----1
(1 row)my_db=# select * from s2.a;id 
----2
(1 row)已经恢复过后，如果重复恢复会报错。报错信息如下：
[postgres@localhost ~]$ psql my_db < aaa
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
ERROR:  schema "s1" already exists
ALTER SCHEMA
ERROR:  schema "s2" already exists
ALTER SCHEMA
SET
SET
ERROR:  relation "a" already exists
ALTER TABLE
ERROR:  relation "a" already exists
ALTER TABLE
COPY 1
COPY 1在默认情况下，psql的脚本即使遇到一个sql错误也会继续执行。如果想让遇到一个sql错误后直接退出该脚本，可以在恢复时手动设置参数ON_ERROR_STOP=on。
[postgres@localhost ~]$ psql --set ON_ERROR_STOP=on my_db < aaa
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
ERROR:  schema "s1" already exists转储一个数据库集簇的全部内容。准备数据
postgres=# create database aaa;
CREATE DATABASE
postgres=# \c aaaaaa=# create table q(id int);
CREATE TABLEaaa=# create schema c1;
CREATE SCHEMA
aaa=# create schema c2;aaa=# create table c1.q(id int);
CREATE TABLE
aaa=# create table c2.q(id int);aaa=# insert into q values(1);
INSERT 0 1
aaa=# select * from q;id 
----1
(1 row)aaa=# insert into c1.q values(2);
INSERT 0 1aaa=# insert into c2.q values(3);
INSERT 0 1aaa=# select * from c1.q;id 
----2
(1 row)aaa=# select * from c2.q;id 
----3
(1 row)postgres=# select datname from pg_database;datname  
-----------postgrestemplate1template0my_dbaaa
(5 rows)备份
[postgres@localhost ~]$ pg_dumpall > bbb
[postgres@localhost ~]$ cat bbb
--
-- PostgreSQL database cluster dump
--SET default_transaction_read_only = off;
…略模拟误删除
postgres=# drop database my_db;
DROP DATABASE
postgres=# drop database aaa;
DROP DATABASE
postgres=# select datname from pg_database;datname  
-----------postgrestemplate1template0
(3 rows)恢复
[postgres@localhost ~]$ psql -f bbb   # 这里面有两个库，如果只想恢复一个，指定库名即可。
SET
SET
SET
psql:bbb:14: ERROR:  role "postgres" already exists
ALTER ROLE
You are now connected to database "template1" as user "postgres".
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
CREATE DATABASE
ALTER DATABASE
You are now connected to database "aaa" as user "postgres".
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
CREATE SCHEMA
ALTER SCHEMA
CREATE SCHEMA
ALTER SCHEMA
SET
SET
CREATE TABLE
ALTER TABLE
CREATE TABLE
ALTER TABLE
CREATE TABLE
ALTER TABLE
COPY 1
COPY 1
COPY 1
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
CREATE DATABASE
ALTER DATABASE
You are now connected to database "my_db" as user "postgres".
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET
CREATE SCHEMA
ALTER SCHEMA
CREATE SCHEMA
ALTER SCHEMA
SET
SET
CREATE TABLE
ALTER TABLE
CREATE TABLE
ALTER TABLE
COPY 2
COPY 2
You are now connected to database "postgres" as user "postgres".
SET
SET
SET
SET
SETset_config 
------------(1 row)SET
SET
SET
SET验证
postgres=# select datname from pg_database;datname  
-----------postgrestemplate1template0aaamy_db
(5 rows)postgres=# \c aaa
You are now connected to database "aaa" as user "postgres".
aaa=# select * from q;id 
----1
(1 row)aaa=# select * from c1.q;id 
----2
(1 row)aaa=# select * from c2.q;id 
----3
(1 row)aaa=# \c my_db;
You are now connected to database "my_db" as user "postgres".my_db=# select * from s1.a;id 
----11
(2 rows)my_db=# select * from s2.a;id 
----22
(2 rows)远程连接相关
dnf安装的pgsql配置文件在
/var/lib/pgsql/data/postgresql.conf源码编译安装的pgsql配置文件在
/usr/local/pgsql/data/postgresql.confpostgresql的默认监听地址是127.0.0.1 想使用别的主机远程连接postgresql，需要修改配置文件。
再开一个终端页，用root身份来修改配置文件，修改之后换回原终端，用postgresql身份登录的终端来重启postgresql。[root@localhost ~]# vim /usr/local/pgsql/data/postgresql.conf 
listen_addresses = '*'          # what IP address(es) to listen on;[postgres@localhost ~]$ pg_ctl -D /usr/local/pgsql/data/ -l logfile restart
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started
[postgres@localhost ~]$ ls
aaa  bbb  logfile
[postgres@localhost ~]$ netstat -anpt | grep postgre
(Not all processes could be identified, non-owned process infowill not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:5432            0.0.0.0:*               LISTEN      12416/postgres      
tcp6       0      0 :::5432                 :::*                    LISTEN      12416/postgres      postgresql默认只能本地访问postgresql，需要修改pg_hba.conf。
[root@localhost ~]# vim /usr/local/pgsql/data/pg_hba.conf 
# IPv4 local connections:
host    all             all             0.0.0.0/0               trust
host    all             all             127.0.0.1/32            trust## 扩展：127.0.0.1/32表示广播、单播、可通信地址都是它。因为子网是32位，只有这一个ip地址。
如果将其更改为127.0.0.1/30 那可用ip为127.0.0.1 127.0.0.2 广播地址为127.0.0.3ip   127.0.0.    000000 00
mask 255.255.255.111111 00网络位          主机位
主机位二进制为00
只有三种排列方式
01	十进制 1
10	十进制 2	
11	十进制 3主机位全1是广播地址。host:连接类型，适用于通过tcp/ip进行的远程连接。all:定义那些数据库可接受这个规则。all：定义了哪些用户可以接受这个规则。0.0.0.0/0：特殊的CIDR（无类别域间路由）表示法，表示任何ip地址。trust：认证方法。trust表示信任，无需任何认证即可访问数据库。[postgres@localhost ~]$ pg_ctl -D /usr/local/pgsql/data/ -l logfile restart
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started客户端
[root@localhost ~]# psql -h 192.168.10.101
psql: 错误: 连接到"192.168.10.101"上的服务器，端口5432失败：No route to host服务器是否在该主机上运行并接受TCP/IP连接?
# 出现此类错误说明，服务端防火墙未关闭或者服务端的服务未监听正确的地址/端口。服务端
[root@localhost ~]# firewall-cmd --add-service=postgresql
success客户端
[root@localhost ~]# psql -h 192.168.10.101
psql: 错误: 连接到"192.168.10.101"上的服务器，端口5432失败：FATAL:  role "root" does not exist
#出现此错误，说明用户未切换到postgres。[root@localhost ~]# useradd postgres
[root@localhost ~]# su - postgres[postgres@localhost ~]$ psql -h 192.168.10.101
psql (15.12, 服务器 15.4)
输入 "help" 来获取帮助信息.postgres=# 服务端
[root@localhost ~]# vim /usr/local/pgsql/data/pg_hba.conf 
# IPv4 local connections:
host    all             all             0.0.0.0/0               md5
host    all             all             127.0.0.1/32            trustpostgres=# alter user postgres with password '123456';
ALTER ROLE[postgres@localhost ~]$ pg_ctl -D /usr/local/pgsql/data/ -l logfile restart
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started客户端
[postgres@localhost ~]$ psql -h 192.168.10.101
用户 postgres 的口令：
psql (15.12, 服务器 15.4)
输入 "help" 来获取帮助信息.postgres=# 忘记密码怎么办？修改pg_hba.conf文件，将本地的MD5更改为trust，重启服务。登录数据库修改密码，再将trust改为md5，重启服务。使用刚修改的密码登录即可。