PostgreSQL 基本使用

第 1 章

• 初识 PostgreSQL

第 2 章

• PostgreSQL 的安装和启动
• pgAdmin 基本操作

第 3 章

• 创建数据库

CREATE DATABASE mytest
WITH ENCODING='UTF8'
OWNER=postgres
CONNECTION LIMIT=-1;

CREATE DATABASE sample_db;

• 删除数据库

DROP DATABASE sample_db;

• 修改数据库

ALTER DATABASE mytest RENAME TO mytest1;

ALTER DATABASE mytest1 OWNER TO postgres1;

第 4 章

• 创建数据表

CREATE TABLE public.ppol
(
    id "char",
    CONSTRAINT isd1 PRIMARY KEY (id)
)
WITH (
	OIDS = FALSE
);

ALTER TABLE public.ppol OWNER TO postgres;


CREATE TABLE tb_empl
(
	id	INT,
	name	VARCHAR(25),
	depId	INT,
	salary	FLOAT
);

CREATE TABLE tb_empl2
(
	id	INT PRIMARY KEY,
	name	VARCHAR(25),
	deptId	INT,
	salary	FLOAT
);

CREATE TABLE tb_empl3
(
	id	INT,
	name	VARCHAR(25),
	deptId	INT,
	salary	FLOAT,
	PRIMARY KEY(id)
);

CREATE TABLE tb_empl
(
	id	INT,
	name	VARCHAR(25),
	deptId	INT,
	salary	FLOAT,
	PRIMARY KEY(name, deptId)
);


-- 外键约束
CREATE TABLE tb_dept1
(
	id	INT PRIMARY KEY,
	name VARCHAR(22) NOT NULL,
	location VARCHAR(50)
);
CREATE TABLE tb_emp5
(
	id	INT PRIMARY KEY,
	name VARCHAR(25),
	depId	INT,
	salary	FLOAT,
	CONSTRAINT fk_emp_dept1 FOREIGN KEY(deptId) REFERENCES tb_dept1(id)
);

• 删除数据表

DROP TABLE IF EXISTS tb_dept2;

-- 删除有关联关系的表时
CREATE TABLE tb_dept2
(
	id	INT PRIMARY KEY,
	name	VARCHAR(22),
	location	VARCHAR(50)
);
CREATE TABLE tb_emp
(
	id	INT PRIMARY KEY,
	name VARCHAR(25),
	deptId INT,
	salary INT,
	CONSTRAINT fk_emp_dept FOREIGN KEY(deptId) REFERENCES tb_dept2(id)
);
DROP TABLE tb_dept2; -- 删除失败（被其它表所依赖）
ALTER TABLE tb_emp DROP CONSTRAINT fk_emp_dept;  -- 删除依赖的外键
DROP TABLE tb_dept2; -- 成功

• 修改数据表

-- 修改字段名称
ALTER TABLE tb_dept1 RENAME location TO loc;

-- 调整字段类型
ALTER TABLE tb_dept1 ALTER COLUMN name TYPE VARCHAR(30);

第 5 章

• 常见运算符介绍
  • 算术
  • 比较
  • 逻辑
  • 位

CREATE TABLE tmp14 (num INT);
INSERT INTO tmp14 VALUES (64);
SELECT num, num+10, num-10, num+5-3, num+36.5 FROM tmp14;

SELECT num, num*2, num/2, num/3, num%3 FROM tmp14;
SELECT 1=0, '2'=2, 2=2, 'b'='b', (1+3)=(2+1), NULL=NULL;
SELECT 'good'<>'god', 1<>2, 4!=4, 5.5!=5, (1+3)!=(2+1), NULL<>NULL;
SELECT 2 IN (1,3,5), 2 NOT IN (1,3,5);
SELECT 'stud' LIKE 'stud', 'stud' LIKE 'stu_', 'stud' LIKE '%d', 'stud' LIKE 't__', 's' LIKE NULL;

• PostgreSQL数据类型

CREATE TABLE tmp1 (x SMALLINT, y INT, z BIGINT);

CREATE TABLE tmp2 (x FLOAT(5), y REAL, z DOUBLE PRECISION);

CREATE TABLE tmp3 (x NUMERIC(5, 1), y NUMERIC (5, 2));
INSERT INTO tmp3(9.12, 9.15);

CREATE TABLE tmp4 (t TIME);
INSERT INTO tmp4 VALUES ('10:05:05 '), ('23:23'), ('101112');
SELECT * FROM tmp4;

ALTER TABLE mp4 ALTER COLUMN t TYPE time WITHOUT time zone;
DELETE FROM tmp4;
INSERT INTO tmp4 VALUES (CURRENT_TIME), (NOW());
SELECT * FROM tmp4;

CREATE TABLE tmp5 (d DATE);
INSERT INTO tmp5 VALUES ('1988-08-08'), ('19980808'), ('20101010');
SELECT * FROM tmp5;

DELETE FROM tmp5;
INSERT INTO tmp5 VALUES(NOW());
SELECT * FROM tmp5;

CREATE TABLE tmp6 VALUES (ts TIMESTAMP);
INSERT INTO tmp7 VALUES ('1996-02-02 02:02:02'), (NOW());
SELECT * FROM tmp7;

CREATE TABLE tmp7h (t TIME WITH TIME ZONE);
INSERT INTO tmp7h VALUES ('10:05:05 PST '), ('10:05:05');
SELECT * FROM tmp7h;

CREATE TABLE tmp8
(
	ch CHARACTER(4),
	vch CHARACTER VARYING (4)
);
INSERT INTO tmp8 VALUES('ab', 'ab'),('abcd', 'abcd'),('ab  ', 'ab  ');
SELECT CONCAT('(', ch, ')'), CONCAT('(', vch, ')') FROM tmp8;
INSERT INTO tmp8 VALUES('abcde', 'abcde');  -- 报错，太长了

CREATE TABLE tmp9 (te TEXT);
INSERT INTO tmp9 VALUES('ab'), ('abcd'), ('ab  ');
SELECT CONCAT('(', te, ')') FROM tmp9;

CREATE TABLE tmp10(b BYTEA);
INSERT INTO tmp10 VALUES(E'\\000');
SELECT * FROM tmp10;

CREATE TABLE tmp11(b BOOLEAN);
INSERT INTO tmp11 VALUES (TRUE),(FALSE),('y'),('no'),('0'); 

CREATE TABLE tmp12(bt int[]);
INSERT INTO tmp12 VALUES ('{{1,1,1},{2,2,2},{3,3,3}}');
SELECT * FROM tmp12;

第 6 章

• 改变数据类型的函数

SELECT CAST(100 AS CHAR(2));
SELECT CAST(100 AS CHAR(100));

• 加密函数

SELECT MD5('mypwd');

SELECT ENCODE('secret', 'hex'), LENGTH(ENCODE('secret', 'hex'));
SELECT DECODE(ENCODE('secret', 'hex'), 'hex'); -- 解密

• 日期和时间函数

SELECT CURRENT_DATE;
SELECT CURRENT_TIME;
SELECT LOCALTIME;
SELECT CURRENT_TIMESTAMP, LOCALTIMESTAMP, NOW();

SELECT EXTRACT(DAY FROM TIMESTAMP ‘2012-09-10 10:18:40');
SELECT EXTRACT(YEAR FROM TIMESTAMP ‘2012-09-10 10:18:40');
SELECT EXTRACT(MONTH FROM TIMESTAMP ‘2012-09-10 10:18:40');
SELECT EXTRACT(DOY FROM TIMESTAMP ‘2012-09-10 10:18:40');  -- 一年中的第几天
SELECT EXTRACT(DOW FROM TIMESTAMP ‘2012-09-10 10:18:40');  -- 一周中的第几天
SELECT EXTRACT(QUARTER FROM TIMESTAMP ‘2012-09-10 10:18:40');  -- 一年中的第几季度

SELECT DATE '2012-09-28' + integer '10'; -- 加 10 天
SELECT DATE '2012-09-28' - integer '10'; 

SELECT DATE '2012-11-01' - DATE '2012-09-10'; -- 相差天数

SELECT 15 * interval '2 day'; -- 30 days

• 数学函数

SELECT ABS(2), ABS(-3, 3), ABS(-33);

SELECT PI();

SELECT SQRT(9), SQRT(40);

SELECT MOD(31, 8), MOD(234, 10), MOD(45.5, 6);

SELECT CEIL(-3.35), CEILING(3.35);
SELECT FLOOR(-3.35), FLOOR(3.35);

SELECT ROUND(-1.14), ROUND(-1.67), ROUND(1.14), ROUND(1.66);

SELECT SIGN(-21), SIGN(0), SIGN(21); -- -1 0 1

SELECT POW(2,2), POWER(2,2), POW(2, -2), POWER(2, -2);

SELECT EXP(3);

SELECT LOG(3);

SELECT RADIANS(90);  -- 角度转弧度
SELECT DEGREES(PI());  -- 弧度转角度

SELECT SIN(1), ROUND(SIN(PI()))；

• 条件判断函数

SELECT
 CASE 2
 WHEN 1 THEN 'one'
 WHEN 2 THEN 'two'
 ELSE 'more'
 END;
 
SELECT
  CASE WHEN 1<0 THEN 'true'
  ELSE 'false'
  END;

• 系统信息函数

SELECT VERSION();

SELECT USER, CURRENT_USER;

• 字符串函数

SELECT CHAR_LENGTH('date'), CHAR_LENGTH('egg');

SELECT LENGTH('date'), LENGTH('egg');

SELECT CONCAT('PostgreSQL', '9.15'), CONCAT('PostgreSQL', NULL, 'SQL');

SELECT CONCAT_WS('-', '1st', '2nd', '3rd'), CONCAT_WS('*', '1st', NULL, '3rd');

SELECT LEFT('FOOTBALL', 5), RIGHT('FOOTBALL', 5);

SELECT LPAD('hello', 4, '??'), LPAD('hello', 10, '??');  -- 填充
SELECT RPAD('hello', 4, '??'), RPAD('hello', 10, '??');

SELECT '( book )', CONCAT('(', LTRIM(' book '), ')');
SELECT '( book )', CONCAT('(', RTRIM(' book '), ')');
SELECT '( book )', CONCAT('(', TRIM(' book '), ')');

SELECT TRIM('xy' FROM 'xyboxyokxyxy'); -- 删除两端的指定字符 xy

SELECT REPEAT('PostgreSQL', 3);

SELECT SUBSTRING('breakfast, 5), SUBSTRING('breakfast', 5, 3), SUBSTRING('lunch', -3);

SELECT REPLACE('xxx.PostgreSQL.com', 'x', w');

第 7 章

• 插入数据

CREATE TABLE person
(
	id	INT NOT NULL,
	name CHAR(40) NOT NULL DEFAULT '',
	age INT NOT NULL DEFAULT 0,
	info CHAR(50) NULL,
	PRIMARY KEY (id)
);

INSERT INTO person (id, name, age, info) VALUES (1, 'Green', 21, 'Lawyer');
SELECT * FROM person;

INSERT INTO person (age, name, id, info) VALUES (22, 'Suse', 2, 'Dancer');
SELECT * FROM person;

INSERT INTO person (3, 'Mary', 24, 'Musician'); -- 此时值的顺序需与定义字段的顺序一致
SELECT * FROM person;

INSERT INTO person (id, name, age) VALUES (4, 'Laura', 25);
SELECT * FROM person;

INSERT INTO person
 (id, name, age, info) 
 VALUES
 (5, 'Evans', 27, 'secretary'),
 (6, 'Dale', 22, 'cook'),
 (7, 'Edison', 28, 'singer');
SELECT * FROM person;

-- 值的顺序需与定义字段的顺序一致
INSERT INTO person
VALUES
(8, 'Harry', 21, 'magician'),
(9, 'Harriet', 19, 'pianist');
SELECT * FROM person;


CREATE TABLE person_old
(
	id INT NOT NULL,
	name CHAR(40) NOT NULL DEFAULT '',
	age INT NOT NULL DEFAULT 0,
	info CHAR(50) NULL,
	PRIMARY KEY (id)
);
INSERT INTO person_old
VALUES
(10, 'Harry', 20, 'student'),
(11, 'Beckham', 31, 'police');
SELECT * FROM person_old;

INSERT INTO person(id, name, age, info)
SELECT id, name, age, info FROM person_old;

• 删除数据

SELECT * FROM person WHERE id = 2;
DELETE * FROM person WHERE id = 2;

SELECT * FROM person WHERE id BETWEEN 4 AND 6;

DELETE FROM person WHERE id BETWEEN 4 AND 6;

DELETE FROM person;

• 更新数据

SELECT * FROM person WHERE id = 10;

UPDATE person SET age = 15, name = 'Liming' WHERE id = 10;

UPDATE person set info='student' WHERE age BETWEEN 19 AND 22;

第 8 章

• 单表查询

SELECT f_name FROM fruits;
SELECT f_name, f_price FROM fruits;

SELECT f_name FROM fruits WHERE f_price = 10.2;
SELECT f_price FROM fruits WHERE f_name='apple';
SELECT f_name, f_price FROM fruits WHERE f_price < 10;

SELECT s_id, f_name, f_price FROM fruits WHERE s_id IN (101, 102) ORDER BY f_name;
-- IN
-- NOT IN
-- BETWEEN AND

-- LIKE '%g%'

-- IS NULL
-- IS NOT NULL

-- AND
-- OR

-- DISTINCT

-- ORDER BY
-- DESC, ASC

-- GROUP BY
-- HAVING

• 合并查询结果

SELECT s_id, f_name, f_price
FROM fruits
WHERE f_price < 9.0
UNION
SELECT s_id, f_name, f_price
FROM fruits
WHERE s_id IN (101, 103);

-- UNION 会去除重复的行
-- UNION ALL 

• 基本查询语句

CREATE TABLE fruits
(
	f_id CHAR(10) NOT NULL,
	s_id INT NOT NULL,
	f_name CHAR(255) NOT NULL,
	f_price DECIMAL(8, 2) NOT NULL,
	PRIMARY KEY (f_id)
);

• 集合函数查询

SELECT COUNT(*) AS cust_num FROM customers;
SELECT COUNT(c_email) AS email_num FROM customers;

SELECT s_id, COUNT(f_name) FROM fruits GROUP BY s_id;

SELECT s_id, MAX(f_price), MIN(f_price), SUM(f_price) AS price_total, AVG(f_price) AS price_avg FROM fruits GROUP BY s_id;

• 连接查询

SELECT suppliers.s_id, s_name, f_name, f_price
FROM fruits, suppliers
WHERE fruits.s_id = suppliers.s_id; 

SELECT suppliers.s_id, s_name, f_name, f_price
FROM fruits INNER JOIN suppliers
ON fruits.s_id = suppliers.s_id;

SELECT f1.f_id, f1.f_name
FROM fruits AS f1, fruits AS f2
WHERE f1.s_id = f2.s_id AND f2.f_id = 'a1';

SELECT customers.c_id, orders.o_num
FROM customers LEFT OUTER JOIN orders
ON customers.c_id = orders.c_id;

-- RIGHT OUTER JOIN

SELECT customers.c_id, orders.o_num
FROM customers INNER JOIN orders
ON customers.c_id = orders.c_id AND customers.c_id = '10001';

• 子查询

SELECT num1 FROM tb1 WHERE num1 > ANY (SELECT num2 FROM tb1);

SELECT num1 FROM tb1 WHERE num1 > ALL (SELECT num2 FROM tb1);

SELECT o_num FROM orders WHERE c_id IN
	(SELECT c_id FROM customers WHERE c_name = 'RedHook');

SELECT s_id, f_name FROM fruits
WHERE s_id =
	(SELECT s1.s_id FROM suppliers AS s1 WHERE s1.s_city = 'Tianjian');

• 为表和字段取别名

SELECT * FROM orders AS o
WHERE o.o_num = 30001;

• 正则表达式查询

SELECT * FROM fruits WHERE f_name ~ '^be'; -- 查询以 be 开头的
SELECT * FROM fruits WHERE f_name ~ 'rry';  -- 查询以 rry 结尾

SELECT * FROM fruits WHERE f_name ~ 'a.g';  -- 含 a + 中间任意字符 + g

SELECT * FROM fruits WHERE f_name ~ '^ba*';

SELECT * FROM fruits WHERE f_name ~ '^ba+';  -- b 开头 + 至少一个 a

SELECT * FROM fruits WHERE f_name ~ 'on'; -- 包含 on
SELECT * FROM fruits WHERE f_name ~ 'on|ap'; -- 包含 on 或 ap

SELECT * FROM fruits WHERE f_name LIKE 'on';
SELECT * FROM fruits WHERE f_name LIKE 'apple';

SELECT * FROM fruits WHERE f_name ~ '[ot]'; -- 匹配 ot 中的任意一个
SELECT * FROM fruits WHERE f_id !~ '[a-e1-2]';  -- 不包含 a-e 及 1-2 的

第 9 章

• 创建索引

CREATE INDEX customers_id ON customers (c_id AS NULLS LAST);
	
-- 普通索引
CREATE INDEX bknameidx ON book(bookname);

-- 唯一索引
CREATE UNIQUE INDEX uniqueidx ON book(bookId);

-- 多列（组合）索引
CREATE INDEX bkauandinfoidx ON book(authors,info);

• 删除索引

DROP INDEX bkauandinfoidx;

• 重命名索引

ALTER INDEX public.bkauandinfoidx RENAME TO bkauandinfoidx2;

第 10 章

• 创建视图

CREATE VIEW view_t AS SELECT quantity, price, quantity * price FROM t;

SELECT * FROM view_t;

CREATE VIEW view_t2(qty, price, total) AS SELECT quantity, price, quantity * price FROM t;

SELECT * FROM view_t2;


CREATE VIEW stu_glass (id, name, glass)
AS
SELECT student.s_id, student.name, stu_info.glass
FROM student, stu_info
WHERE student.s_id = stu_info.s_id;

SELECT * FROM stu_glass;

-- 修改视图名称
ALTER TABLE stu_glass RENAME TO stu_glass1;

• 删除视图

DROP VIEW  IF EXISTS stu_glass;

• 查看视图定义及权限

SELECT * FROM information_schema.views;

第 11 章

• 创建触发器

CREATE TABLE timedb
(
	uid INTEGER,
	gid INTEGER,
	uptime TIMESTAMP WITH TIME ZONE
);

-- 创建触发器函数
CREATE FUNCTION func_timedb() RETURNS trigger AS $func_timedb$
BEGIN
	IF (TG_OP = 'UPDATE') THEN
		IF NEW.uptime = OLD.uptime THEN
			return null;
	END IF;
	UPDATE timedb SET uptime = NOW WHERE uid = NEW.uid AND gid = NEW.gid
	return null;
END;

$func_timedb$ LANGUAGE plpgsql;

-- 创建触发器函数
CREATE TRIGGER timedb_updateTime AFTER INSERT ON timedb
	FOR EACH ROW EXECUTE PROCEDURE func_timedb();

INSERT INTO timedb VALUES(1, 3);
SELECT * FROM timedb;  -- uid 1/gid 3/uptime 2012-12-28 22:29:56.046

• 删除触发器

DROP TRIGGER timedb_updateTime ON timedb;

• 查看和修改触发器

ALTER TRIGGER timedb_updateTime ON timedb RENAME TO timeTrigger;

• 触发器的使用

CREATE TABLE account
(
	id INT,
	name CHAR(20)
);

CREATE FUNCTION account_stam() RETURNS TRIGGER AS $account_stam$
BEGIN
	IF NEW.NAME IS NULL THEN
		RAISE EXCEPTION 'name 字段不能为空值';
	END IF;
END;

$account_stam$ LANGUAGE plpgsql;

CREATE TRIGGER account_stamp BEFORE INSERT ON account
	FOR EACH ROW EXECUTE PROCEDURE account_stam();

INSERT INTO account VALUES (10);  -- 错误：name 字段不能为空值

第 12 章

• 事务管理简介

SELECT * FROM person;

BEGIN;
INSERT INTO person VALUES(1003, '路飞', 80, '10456354');
INSERT INTO person VALUES(1004, '张露', 85, '56423424');
INSERT INTO person VALUES(1005, '魏波', 70, '41242774');
ROLLBACK TRANSACTION;
COMMIT;

SELECT * FROM person;

第 13 章

• 数据库权限管理

ALTER DATABASE test ONWER TO post4;  -- 调整数据库属主

GRANT UPDATE ON book TO postgres; -- 允许用户 postgres 更新 book 表

• 组角色管理

CREATE ROLE post1
	CREATEROLE
		VALID UNTIL 'infinity';
		
CREATE ROLE post2;

SELECT rolname FROM pg_roles;

ALTER ROLE post2 RENAME TO post3;

DROP ROLE post3;

• 组角色和用户权限管理

ALTER ROLE post1 CREATEDB CREATEROLE;  -- 添加创建数据库、创建角度权限

CREATE ROLE postgres1 LOGIN; -- 创建登录角色
ALTER USE postgres1 CREATEDB CREATEROLE;

ALTER USER postgres1 NOCREATEDB NOCREATEROLE; -- 收回权限

• 角色的各种权限

CREATE ROLE post4 LOGIN;  -- 创建登录角色(赋予角色登录权限）

CREATE ROLE post5 SUPERUSER;  -- 创建超级用户

CREATE ROLE post6 CREATEDB;

CREATE ROLE post7 CREATEROLE;

CREATE ROLE post8 PASSWORD '123456';  -- 创建带有口令的角色

第 14 章

• 数据备份

cd C:/Program Files/PostgreSQL/9.1/bin/
pg_dump -U postgres -f C:\test_backup test

# 备份整个数据库
pg_dumpall -U postgres -f C:\dball_backup

• 数据还原

cd C:/Program Files/PostgreSQL/9.1/bin/
psql -d test -U postgres -f C:\test_backup

第 15 章

性能优化

• 优化简介

  优化数据库是数据库管理员和数据库开发人员的必备技能。优化一方面是找出系统的瓶颈，提高数据库整体的性能；另一方面，需要合理的结构设计和参数调整，以提高用户操作响应的速度；同时还要尽可能的节省系统资源，以便系统可以提供更大负荷的服务

• 优化查询

  • 分析查询语句 EXPLAIN
  • 索引对查询速度的影响
  • 优化子查询

• 优化数据库结构

  • 删除索引
  • 使用批量插入
  • 删除外键约束
  • 禁止自动提交
  • 使用 COPY 批量导入

• 优化 PostgreSQL 服务器

  • 优化服务器硬件
  • 优化服务器的参数

第 16 章

高可用、负载均衡和数据复制

• 常见的解决方案

  • 共享磁盘故障转移
  • 文件系统复制
  • 事务日志
  • 基于语句的复制
  • 异步复制
  • 同步复制

• 日志传送备用服务器

  日志传送（log shipping）是一种方法，它自动从主服务器备份事务日志，并使该备份自动对备用服务器可访问。一旦将日志文件放到了备用服务器上，它就可以保持与主服务器的相对同步。

• 数据的流复制

  PostgreSQL 9.0 版本开始提供流复制技术，即备用服务器可以实时同步主服务器，如果备用服务器机器性能足够好，延迟时间可以是毫秒级

• 数据的同步复制

  尽管数据的流复制可以让备用服务器实时地同步主服务器的数据，但是流复制技术依然是异步的。当主服务器崩溃时，备用服务器仍然存在数据丢失的风险。为了解决上面的问题，从 PostgreSQL 9.1 开始，可以支持同步复制技术。

第 17 章

服务器配置与数据库监控

• 服务器配置

  • 服务器配置的文件
  • 连接与认证
  • 资源消耗
  • 预写式日志
  • 查询规划
  • 错误报告和日志
  • 运行时统计
  • 自动清理
  • 客户端连接缺省
  • 锁管理
  • 版本和平台兼容性

• 监控数据库的活动

  • 配置统计收集器
  • 查看收集到的统计信息

• 监控磁盘的使用

  • 监控磁盘的使用量
  • 磁盘满导致的失效

第 18 章

内部结构（Internals）

• 查询经过的路径

• 建立连接

  PostgreSQL 是用一个简单的“每用户一进程”的 client/server 模型来实现的

• 分析器阶段

  • 分析器
  • 转换处理

• PostgreSQL 规则系统（重写系统）

  用于接收分析器阶段创建的查询树，还搜索任何应用到查询树上的规则（存储在系统表里），然后根据给出的规则体进行转换

• 规划器/优化器

  • 规划器/优化器概述
  • 生成可能的规划

• 执行器

  执行器规划器/优化器传过来的查询规划然后递归地处理它，抽取所需要的行集合

编辑记录

06/01/2019 Saturday 14:38