删除原有表首先，我们需要确保所有相关表已经被删除，以避免数据一致性问题。

USE hw7;SET foreign_key_checks = 0;DROP TABLE IF EXISTS airport_codes;DROP TABLE IF EXISTS airport_locations;DROP TABLE IF EXISTS airport_codenames;SET foreign_key_checks = 1;

重新创建表我们需要按照以下顺序创建表：

• 先创建依赖其他表的表
• 然后创建主表，并在主表中定义外键约束

-- 创建空表，供外键约束准备CREATE TABLE airport_locations (    airport_code char(3) NOT NULL,    city varchar(20) NOT NULL,    state char(2) NOT NULL,    PRIMARY KEY (airport_code));-- 创建空表，供外键约束准备CREATE TABLE airport_codenames (    airline_code char(2) NOT NULL,    name varchar(20) NOT NULL,    PRIMARY KEY (airline_code));-- 主表，包含外键约束CREATE TABLE airport_codes (    airport_code char(3) NOT NULL,    airline_code char(2) NOT NULL,    PRIMARY KEY (airport_code, airline_code),    -- 外键约束定义在主表中    FOREIGN KEY (airport_code) REFERENCES airport_locations (airport_code),    FOREIGN KEY (airline_code) REFERENCES airport_codenames (airline_code));

插入数据使用原始数据表（airport_airlines）插入数据到新表中。

-- 插入到 airport_locations 表INSERT INTO airport_locations SELECT DISTINCT airport_code, city, state FROM airport_airlines;-- 插入到 airport_codenames 表INSERT INTO airport_codenames SELECT DISTINCT airline_code, name FROM airport_airlines;-- 插入到 airport_codes 表INSERT INTO airport_codes SELECT DISTINCT airport_code, airline_code FROM airport_airlines;