Execute a scr ipt file connection.sql to create a relational table CONNECTION(FROMCITY, TOCITY, DISTANCE) and load sample data into it. The table contains information between the existing direct connections between the cities (FROMCITY, TOCITY) and
Assignment for Chapter 3 作业内容： Q1. Consider the following bank database, where the primary keys are underlined, construct the following SQL queries for this relational database. branch(branch_name, branch_city, assets) customer (customer name, custo
转载国外的资源。因为最近需要美国城市的数据，所以特地找了找，结果发现了这个版本，有州、市的名字和经纬度坐标，数据全英文。 # U.S. Cities Database The SQL file has **29.880** registered cities. MIT License Copyright (c) 2017 Kelvin S.
代码如下:on delete cascade
当你更新或删除主键表时，那么外键表也会跟随一起更新或删除,需要在建表时设置级联属性
CREATE TABLE Countries(CountryId INT PRIMARY KEY) INSERT INTO Countries (CountryId) VALUES (1) INSERT INTO Countries (CountryId) VALUES (2) INSERT INTO Countries (CountryId) VALUES (3)
