第15次預習課-資料庫mysql

1. 安裝mysql

下載地址：https://dev.mysql.com/downloads/windows/installer/

 2.安裝完後，檢視是否成功

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.將 C:\Program Files\MySQL\MySQL Server 5.7\bin 新增到環境變數path裡。

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

Enter password: ******

show databases;   #檢視資料庫

mysql> create database testmandb;   #新建一個數據庫

mysql> drop database testmandb;  #刪除庫

mysql> use testmandb;   #使用庫

mysql> select database();  #檢視當前使用的庫

mysql> create table user(id int(11));   #建立一個表

mysql> show tables;  #查看錶

mysql> drop table user;  #刪除一個表

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;  #查看錶結構

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

mysql> select * from book;   #查詢表資料

插入除自增的id之外的資料

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

mysql> select count(*) from book;   #查詢數量

mysql> delete from book where id =4;  #刪除id=4的資料

修改：

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

select book_name from book;   #查詢某一列資料

select book_name as 書名 from book;

select id as 序號,book_name as 書名 from book;

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

select * from book where author<>"wulao";  #不等於是<>

select * from book order by price;   #按照價格排序

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;