1528 lines
29 KiB
Markdown
1528 lines
29 KiB
Markdown
# PostgreSQL 使用文档
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## 目录
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1. [安装 PostgreSQL](#一安装-postgresql)
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2. [基本操作](#二基本操作)
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3. [数据库操作](#三数据库操作)
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4. [表操作](#四表操作)
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5. [数据操作（CRUD）](#五数据操作crud)
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6. [索引操作](#六索引操作)
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7. [高级查询](#七高级查询)
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8. [事务管理](#八事务管理)
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9. [常用函数](#九常用函数)
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10. [实用技巧](#十实用技巧)
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---
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## 一、安装 PostgreSQL
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### 1.1 macOS 安装
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#### 方法一：使用 Homebrew（推荐）
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```bash
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# 安装 Homebrew（如果还没有）
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/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
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# 安装 PostgreSQL
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brew install postgresql@15
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# 启动 PostgreSQL 服务
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brew services start postgresql@15
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# 或者手动启动
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pg_ctl -D /usr/local/var/postgresql@15 start
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```
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#### 方法二：使用 Postgres.app（图形化工具）
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1. 访问 https://postgresapp.com/
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2. 下载并安装 Postgres.app
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3. 打开应用，点击 "Initialize" 初始化数据库
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#### 方法三：使用官方安装包
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1. 访问 https://www.postgresql.org/download/macosx/
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2. 下载官方安装包
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3. 按照安装向导完成安装
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### 1.2 Linux 安装
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#### Ubuntu/Debian
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```bash
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# 更新包列表
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sudo apt update
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# 安装 PostgreSQL
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sudo apt install postgresql postgresql-contrib
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# 启动服务
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sudo systemctl start postgresql
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# 设置开机自启
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sudo systemctl enable postgresql
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# 查看服务状态
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sudo systemctl status postgresql
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```
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#### CentOS/RHEL/Fedora
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```bash
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# CentOS/RHEL 7+
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sudo yum install postgresql-server postgresql-contrib
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# 或者使用 dnf (Fedora/CentOS 8+)
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sudo dnf install postgresql-server postgresql-contrib
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# 初始化数据库
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sudo postgresql-setup --initdb
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# 启动服务
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sudo systemctl start postgresql
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sudo systemctl enable postgresql
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```
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#### Arch Linux
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```bash
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# 安装
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sudo pacman -S postgresql
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# 初始化数据库
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sudo -u postgres initdb -D /var/lib/postgres/data
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# 启动服务
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sudo systemctl start postgresql
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sudo systemctl enable postgresql
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```
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### 1.3 验证安装
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```bash
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# 检查 PostgreSQL 版本
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psql --version
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# 或者
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postgres --version
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# 检查服务状态（Linux）
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sudo systemctl status postgresql
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```
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### 1.4 初始配置
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#### 设置 postgres 用户密码
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```bash
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# 切换到 postgres 用户（Linux）
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sudo -u postgres psql
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# 或者直接连接（macOS）
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psql -U postgres
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# 在 psql 中设置密码
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ALTER USER postgres PASSWORD 'your_password';
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```
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#### 创建新用户和数据库
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```bash
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# 使用 postgres 用户登录
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psql -U postgres
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# 创建新用户
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CREATE USER myuser WITH PASSWORD 'mypassword';
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# 创建数据库
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CREATE DATABASE mydb OWNER myuser;
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# 授予权限
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GRANT ALL PRIVILEGES ON DATABASE mydb TO myuser;
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# 退出
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\q
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```
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---
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## 二、基本操作
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### 2.1 连接数据库
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```bash
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# 使用默认用户连接默认数据库
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psql
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# 指定用户和数据库
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psql -U username -d database_name
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# 指定主机和端口
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psql -h localhost -p 5432 -U username -d database_name
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# 使用连接字符串
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psql postgresql://username:password@localhost:5432/database_name
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```
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### 2.2 psql 常用命令
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```sql
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-- 查看所有数据库
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\l
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-- 或者
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\list
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-- 连接到指定数据库
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\c database_name
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-- 或者
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\connect database_name
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-- 查看当前数据库
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SELECT current_database();
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-- 查看所有表
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\dt
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-- 查看表结构
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\d table_name
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-- 查看表详细信息（包括索引、约束等）
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\d+ table_name
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-- 查看所有用户
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\du
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-- 查看当前用户
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SELECT current_user;
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-- 查看帮助
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\?
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-- 查看 SQL 命令帮助
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\h
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-- 查看特定命令帮助
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\h SELECT
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-- 退出 psql
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\q
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-- 或者
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exit
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-- 清屏
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\! clear -- Linux
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\! cls -- Windows
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-- 执行外部 SQL 文件
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\i /path/to/file.sql
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-- 将查询结果导出到文件
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\o /path/to/output.txt
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SELECT * FROM users;
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\o
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-- 显示执行时间
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\timing
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-- 显示查询结果（表格格式）
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\x -- 切换显示模式（横向/纵向）
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-- 查看命令历史
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\s
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-- 保存命令历史到文件
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\s /path/to/history.sql
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```
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---
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## 三、数据库操作
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### 3.1 创建数据库
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```sql
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-- 基本语法
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CREATE DATABASE database_name;
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-- 指定所有者
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CREATE DATABASE database_name OWNER username;
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-- 指定编码
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CREATE DATABASE database_name
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WITH ENCODING 'UTF8';
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-- 完整示例
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CREATE DATABASE vestmind
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OWNER myuser
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ENCODING 'UTF8'
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LC_COLLATE 'zh_CN.UTF-8'
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LC_CTYPE 'zh_CN.UTF-8'
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TEMPLATE template0;
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```
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### 3.2 查看数据库
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```sql
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-- 查看所有数据库
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SELECT datname FROM pg_database;
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-- 查看数据库详细信息
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\l
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-- 或者
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\list
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-- 查看当前数据库
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SELECT current_database();
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```
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### 3.3 删除数据库
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```sql
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-- 删除数据库（需要先断开所有连接）
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DROP DATABASE database_name;
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-- 强制删除（终止所有连接）
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-- 首先终止所有连接
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SELECT pg_terminate_backend(pid)
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FROM pg_stat_activity
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WHERE datname = 'database_name';
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-- 然后删除
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DROP DATABASE database_name;
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```
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### 3.4 修改数据库
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```sql
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-- 重命名数据库
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ALTER DATABASE old_name RENAME TO new_name;
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-- 修改所有者
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ALTER DATABASE database_name OWNER TO new_owner;
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-- 修改连接限制
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ALTER DATABASE database_name WITH CONNECTION LIMIT 10;
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```
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### 3.5 备份和恢复
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```bash
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# 备份数据库
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pg_dump -U username -d database_name > backup.sql
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# 备份为自定义格式（压缩）
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pg_dump -U username -d database_name -F c -f backup.dump
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# 备份所有数据库
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pg_dumpall -U username > all_databases.sql
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# 恢复数据库
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psql -U username -d database_name < backup.sql
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# 恢复自定义格式备份
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pg_restore -U username -d database_name backup.dump
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# 只恢复表结构
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pg_dump -U username -d database_name -s > schema_only.sql
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# 只恢复数据
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pg_dump -U username -d database_name -a > data_only.sql
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```
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---
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## 四、表操作
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### 4.1 创建表
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#### 基本语法
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```sql
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CREATE TABLE table_name (
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column1 datatype constraint,
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column2 datatype constraint,
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...
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);
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```
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#### 数据类型
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**数值类型：**
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```sql
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SMALLINT -- 2字节，-32768 到 32767
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INTEGER -- 4字节，-2147483648 到 2147483647
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BIGINT -- 8字节，大整数
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DECIMAL(p,s) -- 精确数值，p=精度，s=小数位数
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NUMERIC(p,s) -- 同 DECIMAL
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REAL -- 4字节，单精度浮点数
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DOUBLE PRECISION -- 8字节，双精度浮点数
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SERIAL -- 自增整数（1 到 2147483647）
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BIGSERIAL -- 大自增整数
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```
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**字符串类型：**
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```sql
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VARCHAR(n) -- 可变长度字符串，最大n字符
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CHAR(n) -- 固定长度字符串，n字符
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TEXT -- 无限长度字符串
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```
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**日期时间类型：**
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```sql
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DATE -- 日期（年-月-日）
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TIME -- 时间（时:分:秒）
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TIMESTAMP -- 日期和时间
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TIMESTAMPTZ -- 带时区的时间戳
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INTERVAL -- 时间间隔
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```
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**布尔类型：**
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```sql
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BOOLEAN -- true/false
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```
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**JSON 类型：**
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```sql
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JSON -- JSON 数据
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JSONB -- 二进制 JSON（推荐，性能更好）
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```
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#### 约束
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```sql
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-- 主键约束
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id INTEGER PRIMARY KEY
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-- 或者
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id INTEGER,
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PRIMARY KEY (id)
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-- 外键约束
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user_id INTEGER REFERENCES users(id)
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-- 或者
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user_id INTEGER,
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FOREIGN KEY (user_id) REFERENCES users(id)
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-- 唯一约束
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email VARCHAR(100) UNIQUE
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-- 或者
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email VARCHAR(100),
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UNIQUE (email)
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-- 非空约束
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name VARCHAR(50) NOT NULL
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-- 检查约束
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age INTEGER CHECK (age > 0 AND age < 150)
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-- 默认值
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
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-- 自增（使用 SERIAL）
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id SERIAL PRIMARY KEY
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```
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#### 完整示例
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```sql
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-- 创建用户表
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CREATE TABLE users (
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id BIGSERIAL PRIMARY KEY,
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username VARCHAR(50) UNIQUE NOT NULL,
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email VARCHAR(100) UNIQUE,
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phone VARCHAR(20) UNIQUE,
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password_hash VARCHAR(255) NOT NULL,
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nickname VARCHAR(50),
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avatar_url VARCHAR(255),
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status VARCHAR(20) DEFAULT 'active',
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created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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last_login_at TIMESTAMP,
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CHECK (status IN ('active', 'inactive', 'deleted'))
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);
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-- 创建账户表
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CREATE TABLE accounts (
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id BIGSERIAL PRIMARY KEY,
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user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
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name VARCHAR(100) NOT NULL,
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type VARCHAR(20) NOT NULL,
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currency VARCHAR(10) NOT NULL DEFAULT 'CNY',
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description TEXT,
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status VARCHAR(20) DEFAULT 'active',
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created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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CHECK (type IN ('stock', 'fund', 'cash', 'mixed')),
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CHECK (status IN ('active', 'archived', 'deleted'))
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);
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-- 创建持仓表
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CREATE TABLE positions (
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id BIGSERIAL PRIMARY KEY,
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account_id BIGINT NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
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symbol VARCHAR(20) NOT NULL,
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name VARCHAR(100) NOT NULL,
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market VARCHAR(20) NOT NULL,
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shares DECIMAL(18, 4) NOT NULL DEFAULT 0,
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cost_price DECIMAL(18, 4) NOT NULL,
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current_price DECIMAL(18, 4),
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currency VARCHAR(10) NOT NULL DEFAULT 'CNY',
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status VARCHAR(20) DEFAULT 'active',
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created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
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UNIQUE(account_id, symbol, market),
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CHECK (shares >= 0),
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CHECK (status IN ('active', 'suspended', 'delisted'))
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);
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```
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### 4.2 查看表
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```sql
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-- 查看所有表
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\dt
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-- 查看表结构
|
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\d table_name
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-- 查看表详细信息
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\d+ table_name
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-- 查看表的所有列
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SELECT column_name, data_type, is_nullable, column_default
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FROM information_schema.columns
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WHERE table_name = 'users';
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-- 查看表的约束
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SELECT constraint_name, constraint_type
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FROM information_schema.table_constraints
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WHERE table_name = 'users';
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```
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### 4.3 修改表
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```sql
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-- 添加列
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ALTER TABLE table_name
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ADD COLUMN column_name datatype;
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-- 示例
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ALTER TABLE users
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ADD COLUMN age INTEGER;
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-- 删除列
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ALTER TABLE table_name
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DROP COLUMN column_name;
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-- 修改列类型
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ALTER TABLE table_name
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ALTER COLUMN column_name TYPE new_datatype;
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|
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-- 示例
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ALTER TABLE users
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ALTER COLUMN age TYPE SMALLINT;
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|
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-- 重命名列
|
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ALTER TABLE table_name
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RENAME COLUMN old_name TO new_name;
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-- 添加约束
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ALTER TABLE table_name
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ADD CONSTRAINT constraint_name constraint_definition;
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|
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-- 示例：添加外键
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ALTER TABLE accounts
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ADD CONSTRAINT fk_user
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FOREIGN KEY (user_id) REFERENCES users(id);
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|
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-- 删除约束
|
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ALTER TABLE table_name
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DROP CONSTRAINT constraint_name;
|
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|
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-- 重命名表
|
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ALTER TABLE old_table_name
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RENAME TO new_table_name;
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|
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-- 设置列的默认值
|
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ALTER TABLE table_name
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ALTER COLUMN column_name SET DEFAULT default_value;
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|
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-- 删除列的默认值
|
||
ALTER TABLE table_name
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ALTER COLUMN column_name DROP DEFAULT;
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|
||
-- 设置列非空
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||
ALTER TABLE table_name
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ALTER COLUMN column_name SET NOT NULL;
|
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|
||
-- 取消列非空
|
||
ALTER TABLE table_name
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||
ALTER COLUMN column_name DROP NOT NULL;
|
||
```
|
||
|
||
### 4.4 删除表
|
||
|
||
```sql
|
||
-- 删除表
|
||
DROP TABLE table_name;
|
||
|
||
-- 删除表（如果存在）
|
||
DROP TABLE IF EXISTS table_name;
|
||
|
||
-- 级联删除（删除表及其依赖对象）
|
||
DROP TABLE table_name CASCADE;
|
||
|
||
-- 清空表数据（保留表结构）
|
||
TRUNCATE TABLE table_name;
|
||
|
||
-- 清空表数据并重置自增序列
|
||
TRUNCATE TABLE table_name RESTART IDENTITY;
|
||
```
|
||
|
||
---
|
||
|
||
## 五、数据操作（CRUD）
|
||
|
||
### 5.1 插入数据（INSERT）
|
||
|
||
#### 基本语法
|
||
|
||
```sql
|
||
-- 插入单行数据
|
||
INSERT INTO table_name (column1, column2, ...)
|
||
VALUES (value1, value2, ...);
|
||
|
||
-- 插入多行数据
|
||
INSERT INTO table_name (column1, column2, ...)
|
||
VALUES
|
||
(value1, value2, ...),
|
||
(value3, value4, ...),
|
||
(value5, value6, ...);
|
||
|
||
-- 插入所有列（按表定义顺序）
|
||
INSERT INTO table_name
|
||
VALUES (value1, value2, ...);
|
||
|
||
-- 从查询结果插入
|
||
INSERT INTO table_name (column1, column2, ...)
|
||
SELECT column1, column2, ...
|
||
FROM other_table
|
||
WHERE condition;
|
||
```
|
||
|
||
#### 示例
|
||
|
||
```sql
|
||
-- 插入用户
|
||
INSERT INTO users (username, email, password_hash, nickname)
|
||
VALUES ('john_doe', 'john@example.com', 'hashed_password', 'John');
|
||
|
||
-- 插入多用户
|
||
INSERT INTO users (username, email, password_hash, nickname)
|
||
VALUES
|
||
('alice', 'alice@example.com', 'hash1', 'Alice'),
|
||
('bob', 'bob@example.com', 'hash2', 'Bob'),
|
||
('charlie', 'charlie@example.com', 'hash3', 'Charlie');
|
||
|
||
-- 使用 RETURNING 返回插入的数据
|
||
INSERT INTO users (username, email, password_hash)
|
||
VALUES ('david', 'david@example.com', 'hash4')
|
||
RETURNING id, username, created_at;
|
||
|
||
-- 插入时处理冲突（ON CONFLICT）
|
||
INSERT INTO users (username, email, password_hash)
|
||
VALUES ('john_doe', 'john@example.com', 'new_hash')
|
||
ON CONFLICT (username)
|
||
DO UPDATE SET
|
||
email = EXCLUDED.email,
|
||
password_hash = EXCLUDED.password_hash,
|
||
updated_at = CURRENT_TIMESTAMP;
|
||
```
|
||
|
||
### 5.2 查询数据（SELECT）
|
||
|
||
#### 基本语法
|
||
|
||
```sql
|
||
-- 查询所有列
|
||
SELECT * FROM table_name;
|
||
|
||
-- 查询指定列
|
||
SELECT column1, column2, ... FROM table_name;
|
||
|
||
-- 条件查询
|
||
SELECT * FROM table_name WHERE condition;
|
||
|
||
-- 排序
|
||
SELECT * FROM table_name ORDER BY column_name ASC/DESC;
|
||
|
||
-- 限制结果数量
|
||
SELECT * FROM table_name LIMIT number;
|
||
|
||
-- 跳过结果
|
||
SELECT * FROM table_name OFFSET number;
|
||
|
||
-- 组合使用
|
||
SELECT * FROM table_name
|
||
WHERE condition
|
||
ORDER BY column_name DESC
|
||
LIMIT 10 OFFSET 20;
|
||
```
|
||
|
||
#### 示例
|
||
|
||
```sql
|
||
-- 查询所有用户
|
||
SELECT * FROM users;
|
||
|
||
-- 查询指定列
|
||
SELECT id, username, email, created_at FROM users;
|
||
|
||
-- 条件查询
|
||
SELECT * FROM users WHERE status = 'active';
|
||
|
||
-- 多条件查询
|
||
SELECT * FROM users
|
||
WHERE status = 'active' AND created_at > '2024-01-01';
|
||
|
||
-- 模糊查询
|
||
SELECT * FROM users WHERE username LIKE 'john%';
|
||
|
||
-- IN 查询
|
||
SELECT * FROM users WHERE id IN (1, 2, 3, 4, 5);
|
||
|
||
-- BETWEEN 查询
|
||
SELECT * FROM users
|
||
WHERE created_at BETWEEN '2024-01-01' AND '2024-12-31';
|
||
|
||
-- 排序
|
||
SELECT * FROM users ORDER BY created_at DESC;
|
||
|
||
-- 多列排序
|
||
SELECT * FROM users
|
||
ORDER BY status ASC, created_at DESC;
|
||
|
||
-- 限制数量
|
||
SELECT * FROM users LIMIT 10;
|
||
|
||
-- 分页查询
|
||
SELECT * FROM users
|
||
ORDER BY id
|
||
LIMIT 10 OFFSET 0; -- 第1页
|
||
SELECT * FROM users
|
||
ORDER BY id
|
||
LIMIT 10 OFFSET 10; -- 第2页
|
||
|
||
-- 去重
|
||
SELECT DISTINCT status FROM users;
|
||
|
||
-- 聚合函数
|
||
SELECT
|
||
COUNT(*) as total_users,
|
||
COUNT(DISTINCT status) as status_count,
|
||
MAX(created_at) as latest_user,
|
||
MIN(created_at) as earliest_user
|
||
FROM users;
|
||
|
||
-- 分组查询
|
||
SELECT status, COUNT(*) as count
|
||
FROM users
|
||
GROUP BY status;
|
||
|
||
-- HAVING 子句
|
||
SELECT status, COUNT(*) as count
|
||
FROM users
|
||
GROUP BY status
|
||
HAVING COUNT(*) > 10;
|
||
```
|
||
|
||
### 5.3 更新数据（UPDATE）
|
||
|
||
#### 基本语法
|
||
|
||
```sql
|
||
UPDATE table_name
|
||
SET column1 = value1, column2 = value2, ...
|
||
WHERE condition;
|
||
```
|
||
|
||
#### 示例
|
||
|
||
```sql
|
||
-- 更新单列
|
||
UPDATE users
|
||
SET nickname = 'Johnny'
|
||
WHERE id = 1;
|
||
|
||
-- 更新多列
|
||
UPDATE users
|
||
SET
|
||
nickname = 'Johnny',
|
||
email = 'newemail@example.com',
|
||
updated_at = CURRENT_TIMESTAMP
|
||
WHERE id = 1;
|
||
|
||
-- 使用表达式更新
|
||
UPDATE positions
|
||
SET current_price = current_price * 1.1
|
||
WHERE symbol = '600519';
|
||
|
||
-- 基于子查询更新
|
||
UPDATE accounts
|
||
SET status = 'archived'
|
||
WHERE user_id IN (
|
||
SELECT id FROM users WHERE status = 'deleted'
|
||
);
|
||
|
||
-- 更新时返回结果
|
||
UPDATE users
|
||
SET nickname = 'NewName'
|
||
WHERE id = 1
|
||
RETURNING id, username, nickname;
|
||
```
|
||
|
||
### 5.4 删除数据（DELETE）
|
||
|
||
#### 基本语法
|
||
|
||
```sql
|
||
DELETE FROM table_name WHERE condition;
|
||
```
|
||
|
||
#### 示例
|
||
|
||
```sql
|
||
-- 删除指定记录
|
||
DELETE FROM users WHERE id = 1;
|
||
|
||
-- 删除多条记录
|
||
DELETE FROM users WHERE status = 'deleted';
|
||
|
||
-- 删除所有记录（危险！）
|
||
DELETE FROM table_name;
|
||
|
||
-- 使用子查询删除
|
||
DELETE FROM accounts
|
||
WHERE user_id IN (
|
||
SELECT id FROM users WHERE status = 'deleted'
|
||
);
|
||
|
||
-- 删除时返回结果
|
||
DELETE FROM users
|
||
WHERE id = 1
|
||
RETURNING id, username;
|
||
```
|
||
|
||
### 5.5 连接查询（JOIN）
|
||
|
||
```sql
|
||
-- 内连接
|
||
SELECT u.username, a.name as account_name
|
||
FROM users u
|
||
INNER JOIN accounts a ON u.id = a.user_id;
|
||
|
||
-- 左连接
|
||
SELECT u.username, a.name as account_name
|
||
FROM users u
|
||
LEFT JOIN accounts a ON u.id = a.user_id;
|
||
|
||
-- 右连接
|
||
SELECT u.username, a.name as account_name
|
||
FROM users u
|
||
RIGHT JOIN accounts a ON u.id = a.user_id;
|
||
|
||
-- 全外连接
|
||
SELECT u.username, a.name as account_name
|
||
FROM users u
|
||
FULL OUTER JOIN accounts a ON u.id = a.user_id;
|
||
|
||
-- 多表连接
|
||
SELECT
|
||
u.username,
|
||
a.name as account_name,
|
||
p.symbol,
|
||
p.shares
|
||
FROM users u
|
||
INNER JOIN accounts a ON u.id = a.user_id
|
||
INNER JOIN positions p ON a.id = p.account_id
|
||
WHERE u.status = 'active';
|
||
```
|
||
|
||
### 5.6 子查询
|
||
|
||
```sql
|
||
-- 标量子查询
|
||
SELECT
|
||
username,
|
||
(SELECT COUNT(*) FROM accounts WHERE user_id = users.id) as account_count
|
||
FROM users;
|
||
|
||
-- EXISTS 子查询
|
||
SELECT * FROM users u
|
||
WHERE EXISTS (
|
||
SELECT 1 FROM accounts a WHERE a.user_id = u.id
|
||
);
|
||
|
||
-- IN 子查询
|
||
SELECT * FROM users
|
||
WHERE id IN (
|
||
SELECT DISTINCT user_id FROM accounts
|
||
);
|
||
|
||
-- 相关子查询
|
||
SELECT
|
||
u.*,
|
||
(SELECT COUNT(*) FROM accounts WHERE user_id = u.id) as account_count
|
||
FROM users u;
|
||
```
|
||
|
||
---
|
||
|
||
## 六、索引操作
|
||
|
||
### 6.1 索引的作用
|
||
|
||
- 提高查询速度
|
||
- 加速排序和分组
|
||
- 强制唯一性约束
|
||
- 加速表连接
|
||
|
||
### 6.2 创建索引
|
||
|
||
#### 基本语法
|
||
|
||
```sql
|
||
-- 创建单列索引
|
||
CREATE INDEX index_name ON table_name (column_name);
|
||
|
||
-- 创建多列索引
|
||
CREATE INDEX index_name ON table_name (column1, column2, ...);
|
||
|
||
-- 创建唯一索引
|
||
CREATE UNIQUE INDEX index_name ON table_name (column_name);
|
||
|
||
-- 创建部分索引（带条件）
|
||
CREATE INDEX index_name ON table_name (column_name)
|
||
WHERE condition;
|
||
|
||
-- 创建表达式索引
|
||
CREATE INDEX index_name ON table_name (expression);
|
||
```
|
||
|
||
#### 示例
|
||
|
||
```sql
|
||
-- 基本索引
|
||
CREATE INDEX idx_users_email ON users (email);
|
||
|
||
-- 唯一索引
|
||
CREATE UNIQUE INDEX idx_users_username ON users (username);
|
||
|
||
-- 多列索引
|
||
CREATE INDEX idx_transactions_user_date ON transactions (user_id, date);
|
||
|
||
-- 降序索引
|
||
CREATE INDEX idx_users_created_desc ON users (created_at DESC);
|
||
|
||
-- 部分索引（只索引活跃用户）
|
||
CREATE INDEX idx_users_active_email ON users (email)
|
||
WHERE status = 'active';
|
||
|
||
-- 表达式索引
|
||
CREATE INDEX idx_users_lower_email ON users (LOWER(email));
|
||
|
||
-- 文本搜索索引（GIN）
|
||
CREATE INDEX idx_transaction_thoughts_content
|
||
ON transaction_thoughts
|
||
USING gin(to_tsvector('jiebacfg', content));
|
||
```
|
||
|
||
### 6.3 查看索引
|
||
|
||
```sql
|
||
-- 查看表的所有索引
|
||
\d table_name
|
||
|
||
-- 或者
|
||
\di
|
||
|
||
-- 查看索引详细信息
|
||
SELECT
|
||
indexname,
|
||
indexdef
|
||
FROM pg_indexes
|
||
WHERE tablename = 'users';
|
||
|
||
-- 查看索引使用情况
|
||
SELECT
|
||
schemaname,
|
||
tablename,
|
||
indexname,
|
||
idx_scan as index_scans,
|
||
idx_tup_read as tuples_read,
|
||
idx_tup_fetch as tuples_fetched
|
||
FROM pg_stat_user_indexes
|
||
WHERE tablename = 'users';
|
||
```
|
||
|
||
### 6.4 删除索引
|
||
|
||
```sql
|
||
-- 删除索引
|
||
DROP INDEX index_name;
|
||
|
||
-- 删除索引（如果存在）
|
||
DROP INDEX IF EXISTS index_name;
|
||
|
||
-- 级联删除
|
||
DROP INDEX index_name CASCADE;
|
||
```
|
||
|
||
### 6.5 重建索引
|
||
|
||
```sql
|
||
-- 重建索引（释放空间，提高性能）
|
||
REINDEX INDEX index_name;
|
||
|
||
-- 重建表的所有索引
|
||
REINDEX TABLE table_name;
|
||
|
||
-- 重建数据库的所有索引
|
||
REINDEX DATABASE database_name;
|
||
```
|
||
|
||
### 6.6 索引类型
|
||
|
||
```sql
|
||
-- B-tree 索引（默认，最常用）
|
||
CREATE INDEX idx_name ON table_name (column_name);
|
||
|
||
-- Hash 索引（只支持等值查询）
|
||
CREATE INDEX idx_name ON table_name USING HASH (column_name);
|
||
|
||
-- GIN 索引（全文搜索、数组、JSONB）
|
||
CREATE INDEX idx_name ON table_name USING GIN (jsonb_column);
|
||
|
||
-- GiST 索引（几何数据、全文搜索）
|
||
CREATE INDEX idx_name ON table_name USING GIST (geometry_column);
|
||
|
||
-- BRIN 索引（大表，有序数据）
|
||
CREATE INDEX idx_name ON table_name USING BRIN (column_name);
|
||
```
|
||
|
||
### 6.7 索引维护
|
||
|
||
```sql
|
||
-- 分析表（更新统计信息，帮助查询优化器）
|
||
ANALYZE table_name;
|
||
|
||
-- 分析所有表
|
||
ANALYZE;
|
||
|
||
-- 查看索引大小
|
||
SELECT
|
||
pg_size_pretty(pg_relation_size('index_name')) as index_size;
|
||
|
||
-- 查看表和索引总大小
|
||
SELECT
|
||
pg_size_pretty(pg_total_relation_size('table_name')) as total_size;
|
||
```
|
||
|
||
---
|
||
|
||
## 七、高级查询
|
||
|
||
### 7.1 窗口函数
|
||
|
||
```sql
|
||
-- ROW_NUMBER：行号
|
||
SELECT
|
||
id,
|
||
username,
|
||
ROW_NUMBER() OVER (ORDER BY created_at) as row_num
|
||
FROM users;
|
||
|
||
-- RANK：排名（相同值相同排名，跳过后续排名）
|
||
SELECT
|
||
id,
|
||
username,
|
||
RANK() OVER (ORDER BY created_at DESC) as rank
|
||
FROM users;
|
||
|
||
-- DENSE_RANK：密集排名（相同值相同排名，不跳过）
|
||
SELECT
|
||
id,
|
||
username,
|
||
DENSE_RANK() OVER (ORDER BY created_at DESC) as dense_rank
|
||
FROM users;
|
||
|
||
-- 分组窗口函数
|
||
SELECT
|
||
user_id,
|
||
date,
|
||
amount,
|
||
SUM(amount) OVER (PARTITION BY user_id ORDER BY date) as running_total
|
||
FROM transactions;
|
||
```
|
||
|
||
### 7.2 公共表表达式（CTE）
|
||
|
||
```sql
|
||
-- 基本 CTE
|
||
WITH active_users AS (
|
||
SELECT * FROM users WHERE status = 'active'
|
||
)
|
||
SELECT * FROM active_users;
|
||
|
||
-- 递归 CTE
|
||
WITH RECURSIVE category_tree AS (
|
||
-- 基础查询
|
||
SELECT id, name, parent_id, 1 as level
|
||
FROM categories
|
||
WHERE parent_id IS NULL
|
||
|
||
UNION ALL
|
||
|
||
-- 递归查询
|
||
SELECT c.id, c.name, c.parent_id, ct.level + 1
|
||
FROM categories c
|
||
INNER JOIN category_tree ct ON c.parent_id = ct.id
|
||
)
|
||
SELECT * FROM category_tree;
|
||
```
|
||
|
||
### 7.3 集合操作
|
||
|
||
```sql
|
||
-- UNION：合并结果（去重）
|
||
SELECT column1 FROM table1
|
||
UNION
|
||
SELECT column1 FROM table2;
|
||
|
||
-- UNION ALL：合并结果（不去重）
|
||
SELECT column1 FROM table1
|
||
UNION ALL
|
||
SELECT column1 FROM table2;
|
||
|
||
-- INTERSECT：交集
|
||
SELECT column1 FROM table1
|
||
INTERSECT
|
||
SELECT column1 FROM table2;
|
||
|
||
-- EXCEPT：差集
|
||
SELECT column1 FROM table1
|
||
EXCEPT
|
||
SELECT column1 FROM table2;
|
||
```
|
||
|
||
### 7.4 条件表达式
|
||
|
||
```sql
|
||
-- CASE 表达式
|
||
SELECT
|
||
username,
|
||
CASE
|
||
WHEN status = 'active' THEN '活跃'
|
||
WHEN status = 'inactive' THEN '非活跃'
|
||
ELSE '未知'
|
||
END as status_text
|
||
FROM users;
|
||
|
||
-- COALESCE：返回第一个非空值
|
||
SELECT
|
||
username,
|
||
COALESCE(nickname, username) as display_name
|
||
FROM users;
|
||
|
||
-- NULLIF：如果两个值相等返回 NULL
|
||
SELECT NULLIF(column1, column2) FROM table_name;
|
||
|
||
-- GREATEST/LEAST：返回最大/最小值
|
||
SELECT
|
||
GREATEST(price1, price2, price3) as max_price,
|
||
LEAST(price1, price2, price3) as min_price
|
||
FROM products;
|
||
```
|
||
|
||
---
|
||
|
||
## 八、事务管理
|
||
|
||
### 8.1 事务基本概念
|
||
|
||
事务的 ACID 特性：
|
||
- **原子性（Atomicity）**：事务中的所有操作要么全部成功，要么全部失败
|
||
- **一致性（Consistency）**：事务执行前后数据库保持一致状态
|
||
- **隔离性（Isolation）**：并发事务之间相互隔离
|
||
- **持久性（Durability）**：事务提交后，数据永久保存
|
||
|
||
### 8.2 事务操作
|
||
|
||
```sql
|
||
-- 开始事务
|
||
BEGIN;
|
||
-- 或者
|
||
START TRANSACTION;
|
||
|
||
-- 提交事务
|
||
COMMIT;
|
||
|
||
-- 回滚事务
|
||
ROLLBACK;
|
||
|
||
-- 保存点
|
||
SAVEPOINT savepoint_name;
|
||
|
||
-- 回滚到保存点
|
||
ROLLBACK TO SAVEPOINT savepoint_name;
|
||
|
||
-- 释放保存点
|
||
RELEASE SAVEPOINT savepoint_name;
|
||
```
|
||
|
||
### 8.3 事务示例
|
||
|
||
```sql
|
||
-- 基本事务
|
||
BEGIN;
|
||
INSERT INTO users (username, email, password_hash)
|
||
VALUES ('user1', 'user1@example.com', 'hash1');
|
||
INSERT INTO accounts (user_id, name, type)
|
||
VALUES (currval('users_id_seq'), '主账户', 'mixed');
|
||
COMMIT;
|
||
|
||
-- 带错误处理的事务
|
||
BEGIN;
|
||
INSERT INTO users (username, email, password_hash)
|
||
VALUES ('user2', 'user2@example.com', 'hash2');
|
||
-- 如果出错，自动回滚
|
||
SAVEPOINT before_account;
|
||
INSERT INTO accounts (user_id, name, type)
|
||
VALUES (currval('users_id_seq'), '主账户', 'mixed');
|
||
-- 如果账户创建失败，回滚到保存点
|
||
ROLLBACK TO SAVEPOINT before_account;
|
||
COMMIT;
|
||
```
|
||
|
||
### 8.4 事务隔离级别
|
||
|
||
```sql
|
||
-- 设置事务隔离级别
|
||
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
|
||
|
||
-- 查看当前隔离级别
|
||
SHOW transaction_isolation;
|
||
|
||
-- 隔离级别：
|
||
-- READ UNCOMMITTED（PostgreSQL 不支持）
|
||
-- READ COMMITTED（默认）
|
||
-- REPEATABLE READ
|
||
-- SERIALIZABLE
|
||
```
|
||
|
||
---
|
||
|
||
## 九、常用函数
|
||
|
||
### 9.1 字符串函数
|
||
|
||
```sql
|
||
-- 连接字符串
|
||
SELECT CONCAT('Hello', ' ', 'World');
|
||
SELECT 'Hello' || ' ' || 'World';
|
||
|
||
-- 长度
|
||
SELECT LENGTH('Hello');
|
||
SELECT CHAR_LENGTH('Hello');
|
||
|
||
-- 大小写转换
|
||
SELECT UPPER('hello');
|
||
SELECT LOWER('HELLO');
|
||
|
||
-- 截取
|
||
SELECT SUBSTRING('Hello World', 1, 5);
|
||
SELECT LEFT('Hello World', 5);
|
||
SELECT RIGHT('Hello World', 5);
|
||
|
||
-- 替换
|
||
SELECT REPLACE('Hello World', 'World', 'PostgreSQL');
|
||
|
||
-- 去除空格
|
||
SELECT TRIM(' Hello ');
|
||
SELECT LTRIM(' Hello');
|
||
SELECT RTRIM('Hello ');
|
||
|
||
-- 分割字符串
|
||
SELECT SPLIT_PART('a,b,c', ',', 2); -- 返回 'b'
|
||
```
|
||
|
||
### 9.2 数值函数
|
||
|
||
```sql
|
||
-- 绝对值
|
||
SELECT ABS(-10);
|
||
|
||
-- 四舍五入
|
||
SELECT ROUND(3.14159, 2); -- 3.14
|
||
|
||
-- 向上取整
|
||
SELECT CEIL(3.14); -- 4
|
||
|
||
-- 向下取整
|
||
SELECT FLOOR(3.14); -- 3
|
||
|
||
-- 幂运算
|
||
SELECT POWER(2, 3); -- 8
|
||
|
||
-- 平方根
|
||
SELECT SQRT(16); -- 4
|
||
|
||
-- 随机数
|
||
SELECT RANDOM();
|
||
SELECT FLOOR(RANDOM() * 100) + 1; -- 1-100 随机整数
|
||
```
|
||
|
||
### 9.3 日期时间函数
|
||
|
||
```sql
|
||
-- 当前日期时间
|
||
SELECT CURRENT_DATE;
|
||
SELECT CURRENT_TIME;
|
||
SELECT CURRENT_TIMESTAMP;
|
||
SELECT NOW();
|
||
|
||
-- 提取日期部分
|
||
SELECT EXTRACT(YEAR FROM CURRENT_TIMESTAMP);
|
||
SELECT EXTRACT(MONTH FROM CURRENT_TIMESTAMP);
|
||
SELECT EXTRACT(DAY FROM CURRENT_TIMESTAMP);
|
||
|
||
-- 日期加减
|
||
SELECT CURRENT_DATE + INTERVAL '1 day';
|
||
SELECT CURRENT_DATE + INTERVAL '1 month';
|
||
SELECT CURRENT_DATE - INTERVAL '1 year';
|
||
|
||
-- 日期格式化
|
||
SELECT TO_CHAR(CURRENT_TIMESTAMP, 'YYYY-MM-DD HH24:MI:SS');
|
||
SELECT TO_CHAR(CURRENT_DATE, 'YYYY年MM月DD日');
|
||
|
||
-- 日期差
|
||
SELECT CURRENT_DATE - '2024-01-01'::DATE;
|
||
SELECT AGE('2024-12-31'::DATE, '2024-01-01'::DATE);
|
||
```
|
||
|
||
### 9.4 聚合函数
|
||
|
||
```sql
|
||
-- 计数
|
||
SELECT COUNT(*) FROM users;
|
||
SELECT COUNT(DISTINCT status) FROM users;
|
||
|
||
-- 求和
|
||
SELECT SUM(amount) FROM transactions;
|
||
|
||
-- 平均值
|
||
SELECT AVG(price) FROM positions;
|
||
|
||
-- 最大值/最小值
|
||
SELECT MAX(created_at) FROM users;
|
||
SELECT MIN(created_at) FROM users;
|
||
|
||
-- 分组聚合
|
||
SELECT
|
||
status,
|
||
COUNT(*) as count,
|
||
AVG(EXTRACT(YEAR FROM AGE(CURRENT_DATE, created_at))) as avg_age
|
||
FROM users
|
||
GROUP BY status;
|
||
```
|
||
|
||
### 9.5 JSON 函数
|
||
|
||
```sql
|
||
-- 创建 JSON
|
||
SELECT '{"name": "John", "age": 30}'::JSON;
|
||
SELECT JSON_BUILD_OBJECT('name', 'John', 'age', 30);
|
||
|
||
-- 提取 JSON 值
|
||
SELECT '{"name": "John"}'::JSON->>'name';
|
||
SELECT '{"user": {"name": "John"}}'::JSON->'user'->>'name';
|
||
|
||
-- JSON 数组
|
||
SELECT JSON_ARRAY_LENGTH('[1,2,3]'::JSON);
|
||
|
||
-- JSONB 操作符
|
||
SELECT '{"name": "John"}'::JSONB @> '{"name": "John"}'::JSONB; -- 包含
|
||
SELECT '{"name": "John"}'::JSONB ? 'name'; -- 键存在
|
||
```
|
||
|
||
---
|
||
|
||
## 十、实用技巧
|
||
|
||
### 10.1 性能优化
|
||
|
||
```sql
|
||
-- 使用 EXPLAIN 分析查询计划
|
||
EXPLAIN SELECT * FROM users WHERE email = 'test@example.com';
|
||
|
||
-- 详细分析（包含实际执行时间）
|
||
EXPLAIN ANALYZE SELECT * FROM users WHERE email = 'test@example.com';
|
||
|
||
-- 查看慢查询
|
||
SELECT
|
||
query,
|
||
calls,
|
||
total_time,
|
||
mean_time
|
||
FROM pg_stat_statements
|
||
ORDER BY mean_time DESC
|
||
LIMIT 10;
|
||
```
|
||
|
||
### 10.2 数据导入导出
|
||
|
||
```sql
|
||
-- 导出为 CSV
|
||
COPY users TO '/tmp/users.csv' WITH CSV HEADER;
|
||
|
||
-- 从 CSV 导入
|
||
COPY users FROM '/tmp/users.csv' WITH CSV HEADER;
|
||
|
||
-- 导出为文本
|
||
COPY users TO '/tmp/users.txt';
|
||
|
||
-- 从文本导入
|
||
COPY users FROM '/tmp/users.txt';
|
||
```
|
||
|
||
### 10.3 查看数据库信息
|
||
|
||
```sql
|
||
-- 查看数据库大小
|
||
SELECT pg_size_pretty(pg_database_size('database_name'));
|
||
|
||
-- 查看表大小
|
||
SELECT pg_size_pretty(pg_total_relation_size('table_name'));
|
||
|
||
-- 查看所有表大小
|
||
SELECT
|
||
schemaname,
|
||
tablename,
|
||
pg_size_pretty(pg_total_relation_size(schemaname||'.'||tablename)) AS size
|
||
FROM pg_tables
|
||
WHERE schemaname = 'public'
|
||
ORDER BY pg_total_relation_size(schemaname||'.'||tablename) DESC;
|
||
|
||
-- 查看连接数
|
||
SELECT count(*) FROM pg_stat_activity;
|
||
|
||
-- 查看当前连接
|
||
SELECT * FROM pg_stat_activity;
|
||
```
|
||
|
||
### 10.4 权限管理
|
||
|
||
```sql
|
||
-- 授予权限
|
||
GRANT SELECT, INSERT, UPDATE ON table_name TO username;
|
||
GRANT ALL PRIVILEGES ON DATABASE database_name TO username;
|
||
|
||
-- 撤销权限
|
||
REVOKE SELECT ON table_name FROM username;
|
||
|
||
-- 查看权限
|
||
\dp table_name
|
||
```
|
||
|
||
### 10.5 序列操作
|
||
|
||
```sql
|
||
-- 查看当前序列值
|
||
SELECT currval('users_id_seq');
|
||
|
||
-- 查看下一个序列值
|
||
SELECT nextval('users_id_seq');
|
||
|
||
-- 设置序列值
|
||
SELECT setval('users_id_seq', 100);
|
||
|
||
-- 重置序列
|
||
ALTER SEQUENCE users_id_seq RESTART WITH 1;
|
||
```
|
||
|
||
### 10.6 常用配置
|
||
|
||
```sql
|
||
-- 查看配置
|
||
SHOW ALL;
|
||
SHOW shared_buffers;
|
||
SHOW max_connections;
|
||
|
||
-- 设置配置（会话级别）
|
||
SET work_mem = '256MB';
|
||
|
||
-- 查看时区
|
||
SHOW timezone;
|
||
SET timezone = 'Asia/Shanghai';
|
||
```
|
||
|
||
---
|
||
|
||
## 十一、常见问题
|
||
|
||
### 11.1 连接问题
|
||
|
||
```bash
|
||
# 问题：无法连接到数据库
|
||
# 解决：检查 PostgreSQL 服务是否运行
|
||
sudo systemctl status postgresql # Linux
|
||
brew services list # macOS
|
||
|
||
# 问题：认证失败
|
||
# 解决：检查 pg_hba.conf 配置文件
|
||
sudo nano /etc/postgresql/15/main/pg_hba.conf
|
||
```
|
||
|
||
### 11.2 性能问题
|
||
|
||
```sql
|
||
-- 问题：查询慢
|
||
-- 解决：创建索引
|
||
CREATE INDEX idx_column ON table_name (column_name);
|
||
|
||
-- 问题：表膨胀
|
||
-- 解决：VACUUM
|
||
VACUUM ANALYZE table_name;
|
||
|
||
-- 问题：统计信息过期
|
||
-- 解决：更新统计信息
|
||
ANALYZE table_name;
|
||
```
|
||
|
||
### 11.3 数据备份恢复
|
||
|
||
```bash
|
||
# 定期备份脚本
|
||
#!/bin/bash
|
||
DATE=$(date +%Y%m%d_%H%M%S)
|
||
pg_dump -U postgres database_name > /backup/db_$DATE.sql
|
||
|
||
# 自动清理旧备份（保留30天）
|
||
find /backup -name "db_*.sql" -mtime +30 -delete
|
||
```
|
||
|
||
---
|
||
|
||
## 十二、参考资源
|
||
|
||
- **官方文档**：https://www.postgresql.org/docs/
|
||
- **中文文档**：https://www.postgresql.org/docs/current/index.html
|
||
- **psql 命令参考**：https://www.postgresql.org/docs/current/app-psql.html
|
||
- **SQL 语法参考**：https://www.postgresql.org/docs/current/sql.html
|
||
|
||
---
|
||
|
||
**文档版本**：v1.0
|
||
**创建日期**：2024年
|
||
**适用版本**：PostgreSQL 12+
|
||
|