# 第14章_视图(View)课后练习

USE dbtest14;
# 练习1
#1. 使用表employees创建视图employee_vu，其中包括姓名（LAST_NAME），员工号（EMPLOYEE_ID），部门号(DEPARTMENT_ID)
CREATE OR REPLACE VIEW employee_vu(lname,emp_id,dept_id)
AS
    SELECT last_name,employee_id,department_id
FROM emps;

#2. 显示视图的结构
DESC employee_vu;

#3. 查询视图中的全部内容
SELECT *
FROM employee_vu;

#4. 将视图中的数据限定在部门号是80的范围内
CREATE OR REPLACE VIEW employee_vu(lname,emp_id,dept_id)
AS
    SELECT last_name,employee_id,department_id
FROM emps
WHERE department_id = 80;

# 练习2
CREATE TABLE emps
AS
SELECT * FROM atguigudb.employees;
#1. 创建视图emp_v1,要求查询电话号码以‘011’开头的员工姓名和工资、邮箱
CREATE OR REPLACE VIEW emp_v1
AS
    SELECT last_name,salary,email
FROM emps
WHERE phone_number LIKE '011%';

#2. 要求将视图 emp_v1 修改为查询电话号码以‘011’开头的并且邮箱中包含 e 字符的员工姓名和邮箱、电话号码
CREATE OR REPLACE VIEW emp_v1
AS
    SELECT last_name,email,phone_number,salary
FROM emps
WHERE phone_number LIKE '011%'
AND email LIKE '%e%';

SELECT * FROM emp_v1;

#3. 向 emp_v1 插入一条记录，是否可以？

DESC emps;

#实测：失败了
INSERT INTO emp_v1
VALUES ('Tom','tom@126.com','01012345');

#4. 修改emp_v1中员工的工资，每人涨薪1000
SELECT *
FROM emp_v1;

UPDATE emp_v1
SET salary = salary + 1000;

#5. 删除emp_v1中姓名为Olsen的员工
DELETE FROM emp_v1
WHERE last_name = 'Olsen';

#6. 创建视图emp_v2，要求查询部门的最高工资高于 12000 的部门id和其最高工资
CREATE OR REPLACE VIEW emp_v2(dept_id,max_sal)
AS
    SELECT department_id,MAX(salary)
FROM emps
GROUP BY department_id
HAVING MAX(salary) > 12000;

SELECT * FROM emp_v2;

#7. 向 emp_v2 中插入一条记录，是否可以？

# 不可以
# 错误：The target table emp_v2 of the INSERT is not insertable-into
INSERT INTO emp_v2(dept_id,max_sal)
VALUES (4000,20000);

#8. 删除刚才的emp_v2 和 emp_v1
DROP VIEW IF EXISTS emp_v1,emp_v2;

SHOW TABLES;