MYSQL数据库基本操作命令用户名和密码：123456创建一个名称为mydb1的数据库。
create database mydb1;查看所有数据库show databases;创建一个使用utf-8字符集的mydb2数据库。
create database mydb2 character set utf8;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;显示库的创建信息show create database mydb3;删除前面创建的mydb1数据库drop database mydb1;查看服务器中的数据库，并把其中某一个库的字符集修改为gb2312;alter database mydb2 character set gb2312;show create database mydb2;备份库1、准备库的数据create database mydb1;use mydb1;create table test(id int);insert into test(id) values(1);select * from test;2、删除库：drop database mydb1;3、4.1 创建库：create database mydb1;4.2 \. test.sql (通过执行脚本文件实现) 5、创建一个员工表use mydb1; 进入库create table employee(id int,name varchar(20),gender varchar(4),birthday date,entry_date date,job varchar(40),salary double,resume text)character set utf8 collate utf8_general_ci;查看库中所有表show tables;查看表的创建细节show create table employee;查看表的结构desc employee;在上面员工表的基本上增加一个image列。
alter table employee add image blob;修改job列，使其长度为60。
alter table employee modify job varchar(60);删除sex列。
alter table employee drop gender;表名改为user。
rename table employee to user;修改表的字符集alter table user character set gb2312;show create table user;列名name修改为usernamealter table user change column name username varchar(20);使用insert语句向表中插入一个员工的信息。
insert into employee(id,username,birthday,entry_date,job,salary,resume)values(1,'aaa','1980-09-09','1980-09-09','bbb',1000,'bbbbbbbb');查看插入的数据select * from employee;使用insert语句向表中插入一个员工的信息。
insert into employee(id,username,birthday,entry_date,job,salary,resume) values(2,'小李子','1980-09-09','1980-09-09','bbb',1000,'bbbbbbbb');插入失败后的解决方案show variables like 'chara%';set character_set_client=gb2312;显示失败后的解决方案set character_set_results=gb2312;将所有员工薪水修改为5000元。
update employee set salary=5000;将姓名为’aaa’的员工薪水修改为3000元。
update employee set salary=3000 where username='aaa';将姓名为’aaa’的员工薪水修改为4000元,job改为cccupdate employee set salary=4000,job='ccc' where username='aaa';将aaa的薪水在原有基础上增加1000元。
update employee set salary=salary+1000 where username='aaa';删除表中名称为’zs’的记录。
delete from employee where username='小李子';删除表中所有记录。
delete from employee;使用truncate删除表中记录。
truncate table employee;查询表中所有学生的信息。
select id,name,chinese,english,math from student;select * from student;查询表中所有学生的姓名和对应的英语成绩。
select name,english from student;过滤表中重复数据。
select distinct english from student;在所有学生的英语分数上加10分特长分。
select name,english+10 from student;统计每个学生的总分。
select name,(english+chinese+math) from student;使用别名表示学生分数。
select name as 姓名,(english+chinese+math) as 总分 from student;select name 姓名,(english+chinese+math) 总分 from student;查询姓名为王五的学生成绩select * from student where name='王五';查询英语成绩大于90分的同学select * from student where english>90;查询总分大于200分的所有同学select * from student where (english+chinese+math)>200;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;查询数学分数为89,90,91的同学。
select * from student where math=80 or math=90 or math=91;select * from student where math in(80,90,91);查询所有姓李的学生成绩。
select * from student where name like '李%';对数学成绩排序后输出。
select name,math from student order by math;对总分排序后输出，然后再按从高到低的顺序输出select name from student order by (math+english+chinese) desc;对姓李的学生成绩排序输出select name 姓名,(math+english+chinese) 总分from student where name like '李%' order by(math+english+chinese) desc;统计一个班级共有多少学生？select count(*) from student;select count(name) from student;统计数学成绩大于90的学生有多少个？select count(*) from student where math>90;统计总分大于250的人数有多少？select count(*) from student where (math+english+chinese)>250;统计一个班级数学总成绩？select sum(math) from student;统计一个班级语文、英语、数学各科的总成绩select sum(math),sum(chinese),sum(english) from student;统计一个班级语文、英语、数学的成绩总和select sum(chinese+math+english) from student;统计一个班级语文成绩平均分select sum(chinese)/count(chinese) from student;求一个班级数学平均分？select avg(math) from student;求一个班级总分平均分select avg(chinese+english+math) from student;求班级最高分和最低分select max(chinese+english+math),min(chinese+english+math) from student;对订单表中商品归类后，显示每一类商品的总价select product from orders group by product;select product,sum(price) from orders group by product;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;定义带有主键约束的表create table test1 (id int primary key,name varchar(20),password varchar(20));定义一个主键自动增长的表create table test2(id int primary key auto_increment,name varchar(20),password varchar(20));create table test3(id int primary key auto_increment,name varchar(20) unique);create table test4(id int primary key auto_increment,name varchar(20) unique not null);//什么是外键约束create table husband(id int primary key,name varchar(20));create table wife(id int primary key,name varchar(20),husband_id int,constraint husband_id_FK foreign key(husband_id) references husband(id) );//一对多或多对一create table department()create table employee()//多对多create table teacher(id int primary key,name varchar(20),salary double);create table student(id int primary key,name varchar(20));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) );//一对一create table person(id int primary key,name varchar(20));create table idcard(id int primary key,address varchar(40),constraint id_FK foreign key(id) references person(id) );。