SQL实战案例-优快云博客

本文通过具体实例演示了如何使用SQL创建表、插入数据、更新记录及删除操作等基本技能。涵盖教师信息管理、学生成绩录入等多个场景，并展示了条件更新与批量删除的方法。

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插入几条老师信息和成绩、用SQL插入几条员工信息（注意：bit类型，在写代码中用1或0来表示，不要用’false’,会进行类型转换的。）
create table TblTeacher
(
tTId int identity(1,1) primary key,
tTName nvarchar(50) not null,
tTGender bit default(1),
tTAge int,
tTSalary money,
tTBirthday datetime
)

insert into TblTeacher
select '商炳奇',1,22,10000,'1991-10-30' union
select '刘祎',0,22,10000,'1991-11-06' union
select '耿宇丹',0,21,10000,'1992-12-30' union
select '张少丹',0,22,10000,'1991-6-6' union
select '王静静',0,22,10000,'1991-6-6' union
select '段琳琳',0,22,10000,'1991-6-6' union
select '杨巧巧',0,21,10000,'1991-6-6'

create table TblStudent
(
studentId int identity(1,1) primary key,
tScoreId int not null,
sName nvarchar(50) not null,
sAge int not null,
sNo numeric(18,0),--身份证号，十八位数字，小数位0
sEmail varchar(50),
sGender bit default(1),
sBirthday datetime
)

insert into TblStudent
select 1,'刘备',20,123456789012345678,'123@163.com',1,'1987-5-6' union
select 1,'关羽',19,123456789012345671,'1sfdsf3@163.com',1,'1988-8-6' union
select 1,'张飞',18,123456789012345672,'12sfsd3@163.com',1,'1989-5-19' union
select 4,'曹操',22,123456789012345673,'12sf3@163.com',1,'1985-12-6' union
select 4,'夏侯惇',22,123456789012345674,'1ff23@163.com',1,'1985-3-6' union
select 4,'华佗',50,12345678901234565,'12ff3@163.com',1,'1957-1-16' union
select 4,'甄姬',18,12345678901234565,'12f3@163.com',0,'1989-8-8'

create table TblScore
(
tScoreId int identity(1,1) primary key,
studentId int not null, --学生id，外键
tEnglish float,
tMath float
)

insert into TblScore
select 1,90,97 union
select 2,90,70 union
select 3,59,100 union
select 4,100,80 union
select 5,60,96 union
select 6,0,100 union
select 7,80,60

练习1：给studentId是1的英语成绩加10分
update TblScore set tEnglish=tEnglish+10 where studentId=1

练习2：考试题偏难，所有人的成绩加5分
update TblScore
set tEnglish=
(
case when tEnglish+5<=100 then tEnglish+5
when tEnglish+5>=100 then 100
end
),
tMath=
(
case when tMath+5<=100 then tMath+5
when tmath+5>=100 then 100
end
)

练习3：所有女学生的年龄减1岁
update TblStudent set sAge=sAge-1 where sGender=0

删除工资大于2000的老师

delete from TblTeacher where tTSalary>2000
============将老师表清空========
删除所有老师
delete from TblTeacher
删除数据时候把自增长列的值还原成种子

truncate table TblTeacher