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【MySQL】第三周作业
- 1、在数据库example下创建college表。
- 2、在student表上创建视图college_view。
- 3、查看视图college_view的详细结构
- 4、 更新视图。
- 5 、修改视图，
- 6 、删除视图college_view
1、在数据库example下创建college表。
College表内容如下所示
字段名 字段描述 数据类型 主键 外键 非空 唯一 自增number 学号 INT(10) 是 否 是 是 否name 姓名 VARCHAR(20) 否 否 是 否 否major 专业 VARCHAR(20) 否 否 是 否 否age 年龄 INT(5) 否 否 否 否 否
mysql> create database example;
Query OK, 1 row affected (0.04 sec)mysql> show databases;
+--------------------+
| Database |
+--------------------+
| db_test |
| example |
| information_schema |
| mysql |
| performance_schema |
| rele |
| sys |
| user |
+--------------------+
8 rows in set (0.00 sec)mysql> use example;
Database changed
mysql> CREATE TABLE college(-> number INT(10) NOT NULL UNIQUE PRIMARY KEY COMMENT '学号',-> name VARCHAR(20) NOT NULL COMMENT '姓名',-> major VARCHAR(20) NOT NULL COMMENT '专业',-> age INT(5) COMMENT '年龄'-> );
Query OK, 0 rows affected, 2 warnings (0.11 sec)mysql> show tables;
+-------------------+
| Tables_in_example |
+-------------------+
| college |
+-------------------+
1 row in set (0.00 sec)mysql> desc college;
+--------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| number | int | NO | PRI | NULL | |
| name | varchar(20) | NO | | NULL | |
| major | varchar(20) | NO | | NULL | |
| age | int | YES | | NULL | |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.02 sec)
2、在student表上创建视图college_view。
视图的字段包括student_num、student_name、student_age和department。ALGORITHM设置为MERGE类型，并且为视图加上WITH LOCAL CHECK
OPTION条件
mysql> CREATE VIEW-> college_view(student_num,student_name,student_age,department)-> AS SELECT number,name,age,major FROM college-> WITH LOCAL CHECK OPTION;
Query OK, 0 rows affected (0.02 sec)
3、查看视图college_view的详细结构
mysql> show create view college_view \g
+--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+
| View | Create View | character_set_client | collation_connection |
+--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+
| college_view | CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `college_view` (`student_num`,`student_name`,`student_age`,`department`) AS select `college`.`number` AS `number`,`college`.`name` AS `name`,`college`.`age` AS `age`,`college`.`major` AS `major` from `college` WITH LOCAL CHECK OPTION | utf8mb4 | utf8mb4_0900_ai_ci |
+--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+
1 row in set (0.01 sec)
4、 更新视图。
向视图中插入3条记录。记录内容如下表所示
umer name major age
0901 张三 外语 20
0902 李四 计算机 22
0903 王五 计算机 19
mysql> insert into college_view values(0901,'张三',20,'外语');
Query OK, 1 row affected (0.02 sec)mysql> insert into college_view values(0902,'李四',22,'计算机');
Query OK, 1 row affected (0.01 sec)mysql> insert into college_view values(0903,'王五',19,'计算机');
Query OK, 1 row affected (0.21 sec)mysql> select * from college_view;
+-------------+--------------+-------------+------------+
| student_num | student_name | student_age | department |
+-------------+--------------+-------------+------------+
| 901 | 张三 | 20 | 外语 |
| 902 | 李四 | 22 | 计算机 |
| 903 | 王五 | 19 | 计算机 |
+-------------+--------------+-------------+------------+
3 rows in set (0.00 sec)
5 、修改视图，
使其显示专业为计算机的信息，其他条件不变
方法一：
CREATE OR REPLACE ALGORITHM=UNDEFINED VIEW
college_view(student_num,student_name,student_age,department)
AS SELECT number,name,age,major
FROM college WHERE major=’计算机’
WITH LOCAL CHECK OPTION;
方法二：
ALTER ALGORITHM=UNDEFINED VIEW
college_view(student_num,student_name,student_age,department)
AS SELECT number,name,age,major
FROM college WHERE major=’计算机’
WITH LOCAL CHECK OPTION;
mysql> ALTER ALGORITHM=UNDEFINED VIEW-> college_view(student_num,student_name,student_age,department)-> AS SELECT number,name,age,major-> FROM college WHERE major='计算机'-> WITH LOCAL CHECK OPTION;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from college_view;
+-------------+--------------+-------------+------------+
| student_num | student_name | student_age | department |
+-------------+--------------+-------------+------------+
| 902 | 李四 | 22 | 计算机 |
| 903 | 王五 | 19 | 计算机 |
+-------------+--------------+-------------+------------+
2 rows in set (0.01 sec)
6 、删除视图college_view
DROP VIEW college_view;
mysql> drop view college_view;
Query OK, 0 rows affected (0.01 sec)mysql> select * from college_view;
ERROR 1146 (42S02): Table 'rele.college_view' doesn't exist
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