反序列化

The silk is important representation of the chinese ancient civilization,it`s history can go back the five thousand years ago.the silk not only is a higher 纺织品，but also has a number of cultural meaning. By silk road ,the silk can broadcast all over the world, promoting trade and cultural commmuication of the 东西方。In modern.the silk industry continuous innovation,comblineing traditonal art with modern destige.the products wi-- 1. 创建Employees员工表（主键约束、字段类型全部正确）
CREATE TABLE Employees(
ID INT PRIMARY KEY,
Name VARCHAR(50),
Age INT,
Department VARCHAR(50)
);

-- 2. 向员工表插入3条指定数据
INSERT INTO Employees(ID, Name, Age, Department)
VALUES
(202001, 'John', 30, 'HR'),
(202002, 'smith', 25, 'IT'),
(202003, 'Johnson', 28, 'Finance');

-- 3. 创建IT部门专属视图 IT_view（只展示ID、姓名）
CREATE VIEW IT_view AS
SELECT ID, Name
FROM Employees
WHERE Department = 'IT';

--1.查询单次通话时长大于60且类别为“售前咨询”的客户编号、姓名和联系电话
select custom.cno,cname,phone from custom join record on custom.cno=record.cno where duration>60 and type='售前咨询';
--2.查询通话次数不少于3次的客户编号和姓名
select custom.cno,cname from custom join record on custom.cno=record.cno group by custom.cno,cname having count(*)>=3;
--3.查询满意度评价中没有“差”的客服工号和姓名
select staff.sno,sname from staff join record on staff.sno=record.sno where staff.sno not in (select sno from record where evaluation='差');
--4.将客服员工“王晓燕”的级别修改为“高级专员”
update staff set level='高级专员' where sname='王晓燕';
--5.创建客服通话时长视图vps，包含客服工号，客服姓名，通话总时长
create view vps as select staff.sno,sname,sum(duration) as 通话总时长 from staff join record on staff.sno=record.sno group by staff.sno,sname;