PostgreSQL快速入门：psql工具的使用_MySQL

一、psql介绍

psql是PostgreSQL中的一个命令行交互式客户端工具，类似Oracle中的命令行工具sqlplus:

1.允许你交互地键入SQL或命令，然后把它们发出给PostgreSQL服务器，再显示SQL或命令的结果；

2.输入的内容还可以来自一个文件；

3.还提供了一些元命令和多种类似shell的特性来实现书写脚本，以及对对量任务的自动化工作；

二、psql的简单实用

按照前面的步骤，切换su - postgres用户，实用psql工具连接数据库。

1.查看有哪些数据库

postgres=# \l 
                                  List of databases 
   Name    |  Owner   | Encoding |  Collation  |   Ctype   |  Access privileges  
-----------+----------+----------+-------------+-------------+----------------------- 
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |  
 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 
(3 rows)

a.安装好后，默认会有一个叫postgres的数据库，还有两个模板数据库template0和template1；

b.用户再建数据库的时候，默认是从模板数据库template1克隆出来；

c.template0是一个最简化的模板库，创建数据库时，如果明确指定从此数据库集成，将创建一个最简化的数据库；

2.创建数据库osdba

postgres=# CREATE DATABASE osdba; 
CREATE DATABASE 
postgres-# \l 
                                  List of databases 
   Name    |  Owner   | Encoding |  Collation  |    Ctype    |  Access privileges
-----------+----------+----------+-------------+-------------+----------------------- 
 osdba     | postgres | UTF8    | en_US.UTF-8 | en_US.UTF-8 |  
 postgres  | postgres | UTF8    | en_US.UTF-8 | en_US.UTF-8 |  
 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)

3.访问osdba数据库

-bash-4.1$ psql osdba 
psql (8.4.20) 
Type "help" for help.

4.在数据库osdba中创建表t

osdba=# create table t(id int primary key,name varchar(40)); 
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "t_pkey" for table "t" 
CREATE TABLE

5.查看osdb数据库中的表

osdba=# \d 
        List of relations 
 Schema | Name | Type  |  Owner    
--------+------+-------+---------- 
 public | t    | table | postgres 
(1 row)

6.创建数据库testdb后，并连接到testdb数据库

osdba=# CREATE DATABASE testdb; 
CREATE DATABASE 
osdba=# \c testdb 
psql (8.4.20) 
You are now connected to database "testdb". 
testdb=#

三、psql的常用命令

1.\d命令-查看当前数据库中的所有表

osdba-# \d 
        List of relations 
 Schema | Name | Type  |  Owner    
--------+------+-------+---------- 
 public | t    | table | postgres 
(1 row)

2.\d命令-跟一个表命，查看这个表的结构定义

osdba-# \d t 
              Table "public.t" 
 Column |         Type          | Modifiers  
--------+-----------------------+----------- 
 id     | integer               | not null 
 name   | character varying(40) |  
Indexes: 
    "t_pkey" PRIMARY KEY, btree (id)

3.\d命令-可以查看表格t的索引信息

osdba-# \d t_pkey 
Index "public.t_pkey" 
 Column |  Type    
--------+--------- 
 id     | integer 
primary key, btree, for table "public.t"

4.\d命令-跟通配符如*或？

osdba-# \d t* 
              Table "public.t" 
 Column |         Type          | Modifiers  
--------+-----------------------+----------- 
 id     | integer               | not null 
 name   | character varying(40) |  
Indexes: 
    "t_pkey" PRIMARY KEY, btree (id) 
 
Index "public.t_pkey" 
 Column |  Type    
--------+--------- 
 id     | integer 
primary key, btree, for table "public.t"

5.\d+命令，显示比\d命令更加详细的信息，显示与表列关联的注释

osdba-# \d+ 
                    List of relations 
 Schema | Name | Type  |  Owner   |  Size   | Description  
--------+------+-------+----------+---------+------------- 
 public | t    | table | postgres | 0 bytes |  
(1 row)

6.匹配不同对象类型的\d命令，如\dt-只想显示匹配的表；\di-只想显示索引；\ds-只显示序列；\dv-只显示视图；\df-只显示函数等...

osdba-# \dt t* 
        List of relations 
 Schema | Name | Type  |  Owner    
--------+------+-------+---------- 
 public | t    | table | postgres

7.\dn命令-列出所有的schema

osdba-# \dn 
        List of schemas 
        Name        |  Owner    
--------------------+---------- 
 information_schema | postgres 
 pg_catalog         | postgres 
 pg_toast_temp_1    | postgres 
 public             | postgres 
(5 rows)

8.\db命令-显示所有表空间

osdba-# \db 
       List of tablespaces 
    Name    |  Owner   | Location  
------------+----------+---------- 
 pg_default | postgres |  
 pg_global  | postgres |  
(2 rows)

9.\dg-列出数据库中所有角色和用户

osdba-# \dg 
            List of roles 
 Role name | Attributes  | Member of  
-----------+-------------+----------- 
 postgres  | Superuser   | {} 
           : Create role    
           : Create DB

10.\dp-显示表的权限分配情况

osdba-# \dp 
                          Access privileges 
 Schema | Name | Type  | Access privileges | Column access privileges  
--------+------+-------+-------------------+-------------------------- 
 public | t    | table |                   |  
(1 row)

四、指定字符集编译的命令

1.\encoding gbk-设置客户端的字符编码为gbk

五、\pset命令

1.\pset命令-用于设置输出的格式，\pset border 0/1/2：输出内容无边框、只有内边框、内外都有边框

osdba-# \pset border 0 
Border style is 0. 
osdba-# \dp 
                     Access privileges 
Schema Name Type  Access privileges Column access privileges 
------ ---- ----- ----------------- ------------------------ 
public t    table                    
(1 row) 
 
osdba-# \pset border 1 
Border style is 1. 
osdba-# \dp 
                          Access privileges 
 Schema | Name | Type  | Access privileges | Column access privileges  
--------+------+-------+-------------------+-------------------------- 
 public | t    | table |                   |  
(1 row) 
 
osdba-# \pset border 2 
Border style is 2. 
osdba-# \dp 
                           Access privileges 
+--------+------+-------+-------------------+--------------------------+ 
| Schema | Name | Type  | Access privileges | Column access privileges | 
+--------+------+-------+-------------------+--------------------------+ 
| public | t    | table |                   |             | 
+--------+------+-------+-------------------+--------------------------+ 
(1 row)

2.\x命令-可以把表中的每一行的每列数据都拆分为单行展示，如果有一行数据有太多的拆行，显示不下，就可以使用这个命令

osdba-# \x 
Expanded display is on. 
osdba-# \dp 
Access privileges 
+-[ RECORD 1 ]-------------+--------+ 
| Schema                   | public | 
| Name                     | t      | 
| Type                     | table  | 
| Access privileges        |        | 
| Column access privileges |        | 
+--------------------------+--------+ 
 
osdba-# \x 
Expanded display is off. 
osdba-# \dp 
                           Access privileges 
+--------+------+-------+-------------------+--------------------------+ 
| Schema | Name | Type  | Access privileges | Column access privileges | 
+--------+------+-------+-------------------+--------------------------+ 
| public | t    | table |                   |         | 
+--------+------+-------+-------------------+--------------------------+ 
(1 row)

五、psql使用技巧

1.使用上下键把过去使用过的命令或者SQL语句调出来，连续两个tab键表示补全或给出提示输入

osdba-# \d 
\d    \dc   \dD   \dew  \dFd  \dg   \dn   \ds   \dT    
\da   \dC   \des  \df   \dFp  \di   \do   \dS   \du    
\db   \dd   \deu  \dF   \dFt  \dl   \dp   \dt   \dv

2.psql加上-E参数，可以把psql中各种以"\"开头的命令执行的实际SQL打印出来

-bash-4.1$ psql -E postgres 
psql (8.4.20) 
Type "help" for help. 
 
postgres=# \d 
********* QUERY ********** 
SELECT n.nspname as "Schema", 
  c.relname as "Name", 
  CASE c.relkind WHEN &＃39;r&＃39; THEN &＃39;table&＃39; WHEN &＃39;v&＃39; THEN &＃39;view&＃39; WHEN &＃39;i&＃39; THEN &＃39;index&＃39; WHEN &＃39;S&＃39; 
  THEN &＃39;sequence&＃39;WHEN &＃39;s&＃39; THEN &＃39;special&＃39; END as "Type", 
  pg_catalog.pg_get_userbyid(c.relowner) as "Owner" 
FROM pg_catalog.pg_class c 
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace 
WHERE c.relkind IN (&＃39;r&＃39;,&＃39;v&＃39;,&＃39;S&＃39;,&＃39;&＃39;) 
      AND n.nspname <> &＃39;pg_catalog&＃39; 
      AND n.nspname <> &＃39;information_schema&＃39; 
      AND n.nspname !~ &＃39;^pg_toast&＃39; 
  AND pg_catalog.pg_table_is_visible(c.oid) 
ORDER BY 1,2; 
************************** 
 
No relations found

如果你在使用之后，想立即关闭

postgres=# \set ECHO_HIDDEN off 
postgres=# \d 
No relations found.

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