PostgreSql基本操作

PostgreSql安装

• apt-cache show postgresql：查看ubuntu可安装版本信息

• sudo apt-get install postgresql：安装postgresql

• 提供了一个linux用户postgres

  sudo su - postgres # 切换至postgres用户
  psql --version # 查看版本
  psql # 进入sql控制台
  \q # 退出命令
  ALTER USER postgres WITH PASSWORD 'postgres'; # 修改密码，默认密码是随机生成的
  

• 远程连接postgresql

  # 默认端口号5432，用户名postgres，密码postgres
  sudo find / -name "pg_hba.conf" # 搜索配置文件位置 
  cd /etc/postgresql/10/main
  
  # 编辑配置文件，找到”IPv4 local connections:“，添加一行
  # host    all             all             192.168.123.0/24        md5
  sudo vim pg_hba.conf
  
  # 找到listen_addresses = 'localhost'
  # 改为listen_addresses = '*'
  sudo vim postgresql.conf
  
  # 重启数据库
  service postgresql restart
  

简单数据库操作

psql -l # 查看数据库
createdb demo # 创建数据库
psql demo # 切换数据库
dropdb demo

help
select now();
select version();

# 创建表
create table posts(title varchar(255), content text);
\dt;
\d posts;
alter table posts rename to postsdemo;
drop table postsdemo;

# 编写.sql文件
psql demo
\i db.sql # 导入sql

create table posts (
    id serial primary key,
    title varchar(255) not null,
    content text check(length(content) > 8),
    is_draft boolean default TRUE,
    is_del boolean default FALSE,
    created_date timestamp default 'now'
);

insert into posts (title, content) values ('', '');
insert into posts (title, content) values (NULL, '');
insert into posts (title, content) values ('title1', 'content11');
select * from posts;
insert into posts (title, content) values ('title2', 'content2');
insert into posts (title, content) values ('title3', 'content3');
select * from posts;

create table users (
    id serial primary key,
    player varchar(255) not null,
    score real,
    team varchar(255)
);

insert into users (player, score, team) values
('阿A', 28.3, '勇士'),
('阿B', 30.2, '勇士'),
('阿C', 35.6, '勇士'),
('阿D', 27.8, '勇士'),
('阿E', 31.3, '勇士'),
('阿F', 19.8, '勇士');

# 不能用双引号括嘴外层
select * from users where player like '阿_'; # '_'表示一个数据
select * from users where player like '阿%';
select * from users order by score desc limit 3 offset 3;
select distinct team from user;
select team, max(score) from users group by team having max(score) >= 25 order by max(score);

# 方便的函数
length
concat
alias
substring
random

update users set score = 29.1 where ...
delete from user where ...

alter table users add fullname varchar(255);
alter table users drop fullname;
alter table users rename player to nba_player;
alter table users alter nba_player type varchar(100);
create index nba_player_index on users(nba_player);
drop index nba_player_index;

begin;
commit;
rollback;

字段类型

• 数值型：
  • integer(int)
  • real // 浮点
  • serial // 序列型，如自增
• 文字型：
  • char
  • varchar
  • text
• 布尔型：
  • boolean
• 日期型：
  • date
  • time
  • timestamp
• 特色类型：
  • Array
  • 网络地址型（inet)
  • JSON
  • XML

更多详情查看官网