class-notes/2207/MySQL数据库操作综合练习题答案.md

练习一

1

#(1)创建数据库
CREATE DATABASE test04_Market DEFAULT CHARACTER SET utf8;
USE test04_Market;
#(2)创建数据表
CREATE TABLE customers(
	c_num INT(11) PRIMARY KEY	AUTO_INCREMENT,
	c_name VARCHAR(50),
	c_contact VARCHAR(50),
	c_city VARCHAR(50),
	c_birth DATETIME NOT NULL
);
#(3)更改字段的位置
#AFTER/BEFORE 字段名 设置位置在指定字段前/后
ALTER TABLE 表名 MODIFY 字段名 数据类型 AFTER/BEFORE 字段名;
ALTER TABLE customers MODIFY c_contact VARCHAR(50) AFTER c_birth;
#(4)更改字段的数据类型
ALTER TABLE customers MODIFY c_name VARCHAR(70);
#(5)更改字段名
ALTER TABLE customers CHANGE c_contact c_phone VARCHAR(50);
#(6)添加字段
ALTER TABLE customers ADD c_gender CHAR(1);
#(7)更改表名
ALTER TABLE customers RENAME TO customers_info;
#(8)删除字段
ALTER TABLE customers_info DROP c_city;

2

#(1)创建表时 添加外键约束并指定外键约束名称
CREATE TABLE orders(
	o_num INT(11) PRIMARY KEY AUTO_INCREMENT,
	o_date DATE,
	c_id INT(11),
	CONSTRAINT fk_cid FOREIGN KEY(c_id) REFERENCES customers_info(c_num)
);
#(2)
#删除指定外键
ALTER TABLE orders DROP FOREIGN KEY orders_ibfk_1;
#删除指定表
DROP TABLE orders;

---

练习二

#(1)创建表、插入记录
CREATE TABLE pet(
	`name` VARCHAR(20) NOT NULL COMMENT '宠物名称',
	`owner` VARCHAR(20) COMMENT '宠物主人',
	species VARCHAR(20) NOT NULL COMMENT '种类',
	sex CHAR(1) NOT NULL COMMENT '性别',
	birth YEAR NOT NULL COMMENT '出生日期',
	death YEAR COMMENT '死亡日期'
);
INSERT INTO pet()
VALUES
('Fluffy', 'Harold', 'cat', 'f', 2003, 2010),
('Claws', 'Gwen', 'cat', 'm', 2004,NULL ),
('Buffy', NULL, 'dog', 'f', 2009, NULL),
('Fang', 'Benny', 'dog', 'm', 2000, NULL),
('Bowser', 'Diane', 'dog', 'm', 2003, 2009),
('Chirpy', NULL, 'bird', 'f', 2008, NULL);
#(2)更新记录
UPDATE pet
SET `owner` = 'Kevin'
WHERE `name` = 'Fang';
#(3)
UPDATE pet
SET `owner` = 'Kevin'
WHERE `owner` IS NULL;
#(4)
DELETE FROM pet
WHERE death IS NOT NULL;
#(5)
TRUNCATE pet;