以下内容是本人根据方立勋老师的课件总结的,向方老师致敬!
1.创建一个使用utf-8字符集,并带校对规则的mydb3数据库。
create database mydb3 character set utf8 collate utf8_general_ci;
2.查看前面创建的mydb2数据库的定义信息
show create database mydb2;
3.删除前面创建的mydb1数据库
drop database mydb1;
4.修改数据库的字符集为gb2312
alter database mydb2 character set gb2312;
5.备份mydb3库中的数据,并恢复
进入到命令行窗口
5.1. 备份:
mysqldump -uroot -proot mydb3>c:1.sql
5.2. 恢复:
5.2.1. 恢复mydb3库方式1
create database mydb3; source c:1.sql
5.2.2. 恢复mydb3库方式2
create database mydb3; mysql -uroot -proot mydb3<c:1.sql (window命令)
6. 创建一个表
use mydb3; create table employee ( id int, name varchar(20), gender char(1), birthday date, entry_date date, job varchar(40), salary decimal(8,2), resume text )character set utf8;
7. 在上面员工表的基本上增加一个image列。
alter table employee add image blob; show create table employee; (显示表的创建语句) desc employee; (显示表结构)
8. 修改job列,使其长度为60。
alter table employee modify job varchar(60);
9. 删除sex列。
alter table employee drop gender;
10. 表名改为user。
rename table employee to user;
11. 修改表的字符集为utf-8
alter table user character set utf8;
12. 列名name修改为username
alter table user change column name username varchar(40);
13. 使用insert语句向表中插入三个员工的信息。
create table employee( id int, name varchar(20), sex bit(1), birthday date, salary decimal(8,2), entry_date date, resume text ); insert into employee(id,name,sex,birthday,salary,entry_date,resume) values(1,'aaa',1,'1980-09-09',1000,'1980-09-09','aaaaaaaa'); select * from employee; insert into employee(id,name,sex,birthday,salary,entry_date,resume) values('2','bbb',1,'1980-09-09','1000','1980-09-09','aaaaaaaa'); insert into employee values('3','ccc',1,'1980-09-09','1000','1980-09-09','aaaaaaaa'); insert into employee(id,name) values(4,'张三');
14. 若想成功插入中文:
14.1. 查看mysql涉及到编码的所有变量
show variables like 'chara%';
14.2. 改变client的字符集
set character_set_client=gb2312;
14.3. 成功插入中文
insert into employee(id,name) values(4,'张三');
14.4 查看若想不乱码
show variables like 'chara%'; set character_set_client=gb2312; set character_set_results=gb2312; select * from employee;
15. 将所有员工薪水修改为5000元。
update employee set salary=5000;
16. 将姓名为’zs’的员工薪水修改为3000元。
update employee set salary=3000 where name='aaa';
17. 将姓名为’aaa’的员工薪水修改为4000元,job改为ccc。
update employee set salary=4000,entry_date='1980-08-08' where name='aaa';
18. 将wu的薪水在原有基础上增加1000元。
update employee set salary=salary+1000 where name='aaa';
19. 删除表中名称为’zs’的记录。
delete from employee where name='aaa';
20. 删除表中所有记录。
delete from employee; truncate table employee;
21. 查询表中所有学生的信息。
select * from student;
22. 查询表中所有学生的姓名和对应的英语成绩。
select name,english from student;
23. 过滤表中重复数据。
select distinct english from student;
24. 在所有学生的数学分数上加10分特长分。
select name,math+10 from student;
25. 统计每个学生的总分。
select name,(chinese+english+math) from student;
26. 使用别名表示学生分数。
select name as 姓名,(chinese+english+math) as 总分 from student; select name 姓名,(chinese+english+math) 总分 from student;
27. 查询姓名为wu的学生成绩
select * from student where name='王五';
28. 查询英语成绩大于90分的同学
select * from student where english>90;
29. 查询总分大于200分的所有同学
select * from student where (chinese+math+english)>200;
30. 查询英语分数在 80-90之间的同学。
select * from student where english>80 and english<90; select * from student where english between 80 and 90;
31. 查询数学分数为89,90,91的同学。
select * from student where math in(89,90,91);
32. 查询所有姓李的学生成绩。
select * from student where name like '李_';
33. 查询数学分>80,语文分>80的同学。
select * from student where math>80 and chinese>80;
34. 对数学成绩排序后输出。
select name,math from student order by math;
35. 对总分排序后输出,然后再按从高到低的顺序输出
select name 姓名,(chinese+math+english) 总分 from student order by 总分 desc;
36. 对姓李的学生成绩排序输出
select name,(chinese+math+english) 总分 from student where name like '李%' order by 总分 desc;
37. 统计一个班级共有多少学生?
select count(*) from student; select count(name) from student;
38. 统计数学成绩大于90的学生有多少个?
select count(math) from student where math>90;
39. 统计总分大于250的人数有多少?
select count(*) from student where (chinese+math+english)>250;
40. 统计一个班级数学总成绩?
select sum(math) from student;
41. 统计一个班级语文、英语、数学各科的总成绩
select sum(chinese),sum(math),sum(english) from student;
42. 统计一个班级语文、英语、数学的成绩总和
select sum(chinese+math+english) from student;
43. 统计一个班级语文成绩平均分
select sum(chinese)/count(chinese) from student;
44. 求一个班级语文平均分?
select avg(chinese) from student;
45. 求一个班级总分平均分
select avg(chinese+math+english) from student;
46. 求班级最高分和最低分
select max(chinese+math+english),min(chinese+math+english) from student;
47. 对订单表中商品归类后,显示每一类商品的总价
select product,sum(price) from orders group by product;
48. 查询购买了几类商品,并且每类总价大于100的商品
select product from orders group by product having sum(price)>100;
49. 定义主键约束
create table a1 ( id int primary key, name varchar(40) ); create table a2 ( id int primary key auto_increment, name varchar(40) );
50. 定义非空、唯一约束
create table a3 ( id int primary key auto_increment, name varchar(40) unique not null );
51. 定义外键约束
create table husband ( id int primary key, name varchar(40) not null ); create table wife ( id int primary key, name varchar(40) not null, husband_id int, constraint husband_id_FK foreign key(husband_id) references husband(id) );
52. 一对多或多对一的表的设计
create table department ( id int primary key, name varchar(40) ); create table employee ( id int primary key, name varchar(40), salary decimal(8,2), department_id int, constraint department_id_FK foreign key(department_id) references department(id) );
53. 多对多数据的保存
create table teacher ( id int primary key, name varchar(40), salary decimal(8,2) ); create table student ( id int primary key, name varchar(40) ); create table teacher_student ( teacher_id int, student_id int, primary key(teacher_id,student_id), constraint teacher_id_FK foreign key(teacher_id) references teacher(id), constraint student_id_FK foreign key(student_id) references student(id) );
54. 一对一数据的保存
create table person ( id int primary key, name varchar(40) ); create table idcard ( id int primary key, city varchar(100), constraint id_FK foreign key(id) references person(id) );
55. 设计category表,保存无限级分类数据
create table category ( id int primary key, name varchar(40), parent_id int, constraint parent_id_FK foreign key(parent_id) references category(id) );