Mysql作业4

lcanfly2025-11-08 14:23

新建数据库

复制代码 
mysql> create database mydb15_indexstu;
Query OK, 1 row affected (0.01 sec)

mysql> use mydb15_indexstu;
Database changed

新建表

1、学生表student，定义主键，姓名不能重名，性别只能输入勇或女，所在系的默认值是"计算机"，结构如下Student(Sno学号，Sname 姓名，Ssex 性别，Sage 年龄，sdept 所在系)Sno为主键

复制代码 
mysql> create table Student(
    -> Sno int primary key auto_increment,
    -> Sname varchar(30) not null unique,
    -> Ssex varchar(2) check (Ssex='男' or Ssex='女') not null,
    -> Sage int not null,
    -> Sdept varchar(10) default '计算机' not null ) ;
Query OK, 0 rows affected (0.02 sec)

mysql> desc  Student;
+-------+-------------+------+-----+-----------+----------------+
| Field | Type        | Null | Key | Default   | Extra          |
+-------+-------------+------+-----+-----------+----------------+
| Sno   | int         | NO   | PRI | NULL      | auto_increment |
| Sname | varchar(30) | NO   | UNI | NULL      |                |
| Ssex  | varchar(2)  | NO   |     | NULL      |                |
| Sage  | int         | NO   |     | NULL      |                |
| Sdept | varchar(10) | NO   |     | 计算机    |                |
+-------+-------------+------+-----+-----------+----------------+
5 rows in set (0.00 sec)

2、用SQL语句创建课程表：Course(Cno课程号，Cname课程名)Cno为主键

复制代码 
mysql> create table Sc(
    -> Sno int not null,
    -> Cno varchar(10) primary key not null,
    -> Score int not null );
Query OK, 0 rows affected (0.02 sec)

mysql> desc Sc;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| Sno   | int         | NO   |     | NULL    |       |
| Cno   | varchar(10) | NO   | PRI | NULL    |       |
| Score | int         | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

3.用SQL语句创建选课表：sc(Sno学号，Cno 课程号，score成绩)Sno,Cno为主键

复制代码 
mysql> create table Course (
    -> Cno int priarmy key not null,
    -> Cname varchar(20) not null ) ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'priarmy key not null,
Cname varchar(20) not null )' at line 2
mysql> create table Course ( Cno int primary key not null, Cname varchar(20) not null );
Query OK, 0 rows affected (0.01 sec)

mysql> desc  Course;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| Cno   | int         | NO   | PRI | NULL    |       |
| Cname | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

处理表

1、修改student 表中年龄(sage)字段属性，数据类型由int 改变为smallint

复制代码 
mysql>
mysql> alter table Student modify Sage smallint;
Query OK, 0 rows affected (0.03 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc  Student;
+-------+-------------+------+-----+-----------+----------------+
| Field | Type        | Null | Key | Default   | Extra          |
+-------+-------------+------+-----+-----------+----------------+
| Sno   | int         | NO   | PRI | NULL      | auto_increment |
| Sname | varchar(30) | NO   | UNI | NULL      |                |
| Ssex  | varchar(2)  | NO   |     | NULL      |                |
| Sage  | smallint    | YES  |     | NULL      |                |
| Sdept | varchar(10) | NO   |     | 计算机    |                |
+-------+-------------+------+-----+-----------+----------------+
5 rows in set (0.00 sec)

2、为course表中Cno课程号字段设置索引，并查看索引

复制代码 
mysql> desc Course;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| Cno   | int         | NO   | PRI | NULL    |       |
| Cname | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> create index Course_Cno on Course(Cno);
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> show index from  Course;
+--------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table  | Non_unique | Key_name   | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type |Comment | Index_comment | Visible | Expression |
+--------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Course |          0 | PRIMARY    |            1 | Cno         | A         |           0 |     NULL |   NULL |      | BTREE      |        |               | YES     | NULL       |
| Course |          1 | Course_Cno |            1 | Cno         | A         |           0 |     NULL |   NULL |      | BTREE      |        |               | YES     | NULL       |
+--------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.01 sec)

mysql> show index from  Course\G
*************************** 1. row ***************************
        Table: Course
   Non_unique: 0
     Key_name: PRIMARY
 Seq_in_index: 1
  Column_name: Cno
    Collation: A
  Cardinality: 0
     Sub_part: NULL
       Packed: NULL
         Null:
   Index_type: BTREE
      Comment:
Index_comment:
      Visible: YES
   Expression: NULL
*************************** 2. row ***************************
        Table: Course
   Non_unique: 1
     Key_name: Course_Cno
 Seq_in_index: 1
  Column_name: Cno
    Collation: A
  Cardinality: 0
     Sub_part: NULL
       Packed: NULL
         Null:
   Index_type: BTREE
      Comment:
Index_comment:
      Visible: YES
   Expression: NULL
2 rows in set (0.00 sec)

3、为Sc表建立按学号(sno)和课程号(cno)组合的升序的主键索引，索引名为sc_index

复制代码 
mysql> create unique index Sc_index on Sc(Sno asc ,Cno asc);
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> show index from Sc\G
*************************** 1. row ***************************
        Table: Sc
   Non_unique: 0
     Key_name: PRIMARY
 Seq_in_index: 1
  Column_name: Cno
    Collation: A
  Cardinality: 0
     Sub_part: NULL
       Packed: NULL
         Null:
   Index_type: BTREE
      Comment:
Index_comment:
      Visible: YES
   Expression: NULL
*************************** 2. row ***************************
        Table: Sc
   Non_unique: 0
     Key_name: Sc_index
 Seq_in_index: 1
  Column_name: Sno
    Collation: A
  Cardinality: 0
     Sub_part: NULL
       Packed: NULL
         Null:
   Index_type: BTREE
      Comment:
Index_comment:
      Visible: YES
   Expression: NULL
*************************** 3. row ***************************
        Table: Sc
   Non_unique: 0
     Key_name: Sc_index
 Seq_in_index: 2
  Column_name: Cno
    Collation: A
  Cardinality: 0
     Sub_part: NULL
       Packed: NULL
         Null:
   Index_type: BTREE
      Comment:
Index_comment:
      Visible: YES
   Expression: NULL
3 rows in set (0.01 sec)

4、创建一视图stu_info,查询全体学生的姓名，性别，课程名，成绩

复制代码 
mysql> select Sname '姓名' , Ssex '性别' , Cname '课程名' , Score '成绩'
    -> from Student join Sc on Student.Sno=Sc.Sno join Course on Sc.Cno=Course.Cno;
Empty set (0.00 sec)

mysql> create view stu_info as select Sname '姓名' , Ssex '性别' , Cname '课程名' , Score '成绩' from Student join Sc on Student.Sno=Sc.Sno join Course on Sc.Cno=Course.Cno;
Query OK, 0 rows affected (0.00 sec)

mysql> show tables;
+---------------------------+
| Tables_in_mydb15_indexstu |
+---------------------------+
| Course                    |
| Sc                        |
| Student                   |
| stu_info                  |
+---------------------------+
4 rows in set (0.00 sec)

5、删除所有索引

复制代码 
mysql> drop index Sc_index on Sc;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> drop index Course_Cno on Course;
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0
相关推荐
全栈老石3 小时前
拆解低代码引擎核心：元数据驱动的"万能表"架构
数据库·低代码
倔强的石头_1 天前
kingbase备份与恢复实战（二）—— sys_dump库级逻辑备份与恢复（Windows详细步骤）
数据库
jiayou642 天前
KingbaseES 实战：深度解析数据库对象访问权限管理
数据库
于眠牧北2 天前
MySQL的锁类型，表锁，行锁，MVCC中所使用的临键锁
mysql
李广坤3 天前
MySQL 大表字段变更实践（改名 + 改类型 + 改长度）
数据库
Turnip12024 天前
深度解析：为什么简单的数据库"写操作"会在 MySQL 中卡住？
后端·mysql
爱可生开源社区4 天前
2026 年，优秀的 DBA 需要具备哪些素质？
数据库·人工智能·dba
随逸1774 天前
《从零搭建NestJS项目》
数据库·typescript
加号35 天前
windows系统下mysql多源数据库同步部署
数据库·windows·mysql
シ風箏5 天前
MySQL【部署 04】Docker部署 MySQL8.0.32 版本（网盘镜像及启动命令分享）
数据库·mysql·docker
热门推荐
01GitHub 镜像站点02OpenClaw 使用和管理 MCP 完全指南03OpenClaw + 飞书（Feishu）环境搭建指南04【OpenClaw 本地实战 Ep.3】突破瓶颈：强制修改 openclaw.json 解锁 32k 上下文记忆05Claude Code + GLM4.7 避坑指南：解决 Unable to connect to Anthropic services06OpenClaw优化飞书API 额度已耗尽问题07Clawdbot部署教程：解决‘gateway token missing’授权问题的完整步骤08Window 10部署openclaw报错node.exe : npm error code 12809OpenClaw大龙虾机器人完整安装教程10小黑课堂计算机二级WPSoffice题库软件下载安装教程（2026年3月最新版）