第15次预习课-数据库mysql-20181017

第15次预习课-数据库mysql

1. 安装mysql

下载地址：https://dev.mysql.com/downloads/windows/installer/

 2.安装完后，查看是否成功

C:\Users\Xue Feifei>cd C:\Program Files\MySQL\MySQL Server 5.7\bin

C:\Program Files\MySQL\MySQL Server 5.7\bin>mysql -V

mysql  Ver 14.14 Distrib 5.7.23, for Win64 (x86_64)

 3.将 C:\Program Files\MySQL\MySQL Server 5.7\bin 添加到环境变量path里。

C:\Users\Xue Feifei>mysql.exe -uroot -h127.0.0.1 -P3306 -p

Enter password: ******

show databases;   #查看数据库

 

mysql> create database testmandb;   #新建一个数据库

 

mysql> drop database testmandb;  #删除库

 

mysql> use testmandb;   #使用库

 

mysql> select database();  #查看当前使用的库

 

mysql> create table user(id int(11));   #创建一个表

mysql> show tables;  #查看表

 

mysql> drop table user;  #删除一个表

 

建立表

create table book(

    id INT NOT NULL AUTO_INCREMENT,

    book_name VARCHAR(100) NOT NULL,

    author VARCHAR(40) NOT NULL,

    publish_date DATE,

    price float,

    PRIMARY KEY(id)

)ENGINE=InnoDB DEFAULT CHARSET=utf8;

mysql> desc book;  #查看表结构

 

mysql> insert into book values(1,"selenium","wulao","2018-1-1",50);   #插入数据

 

mysql> select * from book;   #查询表数据

 

插入除自增的id之外的数据

insert into book(book_name,author,publish_date,price) values("mangodb","zhanglao","2019-3-1",100);

 

mysql> select count(*) from book;   #查询数量

 

mysql> delete from book where id =4;  #删除id=4的数据

 

修改：

update book set book_name="gloryroad db" where book_name = "bdb";

 

select book_name from book;   #查询某一列数据

 

select book_name as 书名 from book;

 

select id as 序号,book_name as 书名 from book;

 

mysql> select * from book where id>=6;

 

select * from book where author<>"wulao";  #不等于是<>

 

select * from book order by price;   #按照价格排序

 

select * from book order by price asc;  升序

select * from book order by price desc; 降序

 

select author,count(*) from book group by author;

 

select author,avg(price) from book group by author; 

 

select author,sum(price) from book group by author having sum(price)>200;