3. 高级特性

一、视图 CREATE VIEW

为查询创建一个视图，为该视图命名，可以像引用普通表一样引用它：

CREATE VIEW view1 AS 
SELECT w.city, w.temp_lo, w.temp_hi, w.prcp, w.date, c.location FROM weather w JOIN cities c ON w.city = c.name;

# 删除视图
DROP VIEW view1;

二、外键

CREATE TABLE cities (
    name varchar(80) primary key, 
    location point
);

CREATE TABLE weather (
    city varchar(80) references cities(name), 
    temp_lo int,
    temp_hi int,
    prcp real,
    date date
);

INSERT INTO cities VALUES('xian', '(88.0, 99.0)');

三、事务

四、窗口函数

五、继承

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