数据库

数据库学习

MySQL

单机程序（自己DB）

单机程序（公用DB）

MySQL：是用于管理文件的一个软件
- 服务端软件
- socket服务端
- 本地文件操作
- 解析指令【SQL语句】
- 客户端软件（各种各样）
- socket客户端
- 发送指令
- 解析指令【SQL语句】

PS:
- DBMS数据库管理系统
- SQL语句

技能：
- 安装 服务端和客户端
- 连接
- 学习SQL语句规则；指示服务端做任意操作

其他类似软件：
关系型数据库：sqllite,db2,oracle,access,sql server MySQL
非关系型数据库：MongoDB,redis

1. MySQL安装

Windows:
可执行文件
点点点
压缩包
放置任意目录
初始化
服务端：E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64inmysqld --initialize-insecure
# 用户名 root 密码：空
启动服务端：
E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64inmysqldmysqld

客户端连接：
E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64inmysqldmysql -u root -p

发送指令：
show databases;
create database db1;

环境变量的配置：
E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64in
mysqld

windows服务：
E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64inmysqld --install
net start MySQL

E:wupeiqimysql-5.7.16-winx64mysql-5.7.16-winx64inmysqld --remove

net start MySQL
net stop MySQL

2. 关于连接

文件夹【数据库】
文件【表】
数据行【行】
数据行
数据行

连接：

默认：用户root


show databases;

use 数据库名称;

show tables;

select * from 表名;

select name,age,id from 表名;

mysql数据库user表
use mysql;
select user,host from user;

创建用户：
create user 'alex'@'192.168.1.1' identified by '123123';
create user 'alex'@'192.168.1.%' identified by '123123';
create user 'alex'@'%' identified by '123123';
授权：
权限 人

grant select,insert,update on db1.t1 to 'alex'@'%';
grant all privileges on db1.t1 to 'alex'@'%';

revoke all privileges on db1.t1 from 'alex'@'%';

DBA: 用户名密码

3. 学习SQL语句规则

操作文件夹
create database db2;
create database db2 default charset utf8; *****
show databases;
drop database db2;

操作文件
show tables;
create table t1(id int,name char(10)) default charset=utf8;
create table t1(id int,name char(10))engine=innodb default charset=utf8;
create table t3(id int auto_increment,name char(10))engine=innodb default charset=utf8; *****

create table t1(
列名 类型 null,
列名 类型 not null,
列名 类型 not null auto_increment primary key,
id int,
name char(10)
)engine=innodb default charset=utf8;
# innodb 支持事务，原子性操作
# myisam myisam

auto_increment 表示：自增
primary key： 表示 约束(不能重复且不能为空); 加速查找
not null: 是否为空
数据类型：

数字：
tinyint
int
bigint

FLOAT
0.00000100000123000123001230123
DOUBLE
0.00000000000000000000100000123000123001230123
0.00000100000123000000000000000
decimal
0.1

字符串：
char(10) 速度快()
root
root
varchar(10) 节省空间
root
PS: 创建数据表定长列往前放

text

上传文件：
文件存硬盘
db存路径
时间类型
DATETIME

enum
set


create table t1(
id int signed not null auto_increment primary key,
num decimal(10,5),
name char(10)
)engine=innodb default charset=utf8;

清空表：
delete from t1;
truncate table t1;
删除表：
drop table t1;

操作文件中内容
插入数据：
insert into t1(id,name) values(1,'alex');
删除：
delete from t1 where id<6
修改：
update t1 set age=18;
update t1 set age=18 where age=17;
查看数据：
select * from t1;

外键：

create table userinfo(
uid int auto_increment primary key,
name varchar(32),
department_id int,
xx_id int,
constraint fk_user_depar foreign key (department_id) references color(id)
)engine=innodb default charset=utf8;

create table department(
id bigint auto_increment primary key,
title char(15)
)engine=innodb default charset=utf8;
innodb原子操作

今日内容参考博客：
http://www.cnblogs.com/wupeiqi/articles/5713315.html
作业：
http://images2015.cnblogs.com/blog/425762/201608/425762-20160803224643778-2071849037.png
http://www.cnblogs.com/wupeiqi/articles/5729934.html

1. 以ATM引出DBMS
2. MySQL
- 服务端
- 客户端
3. 通信交流
- 授权
- SQL语句
- 数据库
create database db1 default charset=utf8;
drop database db1;

- 数据表
先创建tb2部门表

create table tb1用户表(
id int not null auto_increment primary key,
name char(10),
department_id int,
p_id int,
constraint fk_1 foreign key (department_id,p_id) references tb2(tid,xid)
)engine=innodb default charset=utf8;


补充：主键
一个表只能有一个主键
主键可以由多列组成


补充：外键 ?
CREATE TABLE t5 (
nid int(11) NOT NULL AUTO_INCREMENT,
pid int(11) not NULL,
num int(11),
primary key(nid,pid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

create table t6(
id int auto_increment primary key,
name char(10),
id1 int,
id2 int,
CONSTRAINT fk_t5_t6 foreign key (id1,id2) REFERENCES t1(nid,pid)
)engine=innodb default charset=utf8;



- 数据行

insert into tb1(name,age) values('alex',18);
insert into tb1(name,age) values('alex',18),('egon',19),('yuan',20);

delete from tb1;
truncate table tb1;
delete from tb1 where id > 10


update tb1 set name='root' where id > 10

select * from tb;
select id,name from tb;


4 对于自增补充：
desc t10;

show create table t10;

show create table t10 G;

alter table t10 AUTO_INCREMENT=20;


MySQL: 自增步长
基于会话级别：
show session variables like 'auto_inc%'; 查看全局变量
set session auto_increment_increment=2; 设置会话步长
# set session auto_increment_offset=10;
基于全局级别：
show global variables like 'auto_inc%'; 查看全局变量
set global auto_increment_increment=2; 设置会话步长
# set global auto_increment_offset=10;


SqlServer：自增步长：
基础表级别：
CREATE TABLE `t5` (
`nid` int(11) NOT NULL AUTO_INCREMENT,
`pid` int(11) NOT NULL,
`num` int(11) DEFAULT NULL,
PRIMARY KEY (`nid`,`pid`)
) ENGINE=InnoDB AUTO_INCREMENT=4, 步长=2 DEFAULT CHARSET=utf8

CREATE TABLE `t6` (
`nid` int(11) NOT NULL AUTO_INCREMENT,
`pid` int(11) NOT NULL,
`num` int(11) DEFAULT NULL,
PRIMARY KEY (`nid`,`pid`)
) ENGINE=InnoDB AUTO_INCREMENT=4, 步长=20 DEFAULT CHARSET=utf8


今日内容：
0. 唯一索引

create table t1(
id int ....,
num int,
xx int,
unique 唯一索引名称 (列名,列名),
constraint ....
)
#
1 1 1
2 1 2
PS:
唯一：
约束不能重复（可以为空）
PS: 主键不能重复（不能为空）
加速查找

1. 外键的变种

a. 用户表和部门表

用户：
1 alex 1
2 root 1
3 egon 2
4 laoyao 3

部门:
1 服务
2 保安
3 公关
===》 一对多
b. 用户表和博客表
用户表：
1 alex
2 root
3 egon
4 laoyao
博客表：
FK() + 唯一
1 /yuanchenqi/ 4
2 /alex3714/ 1
3 /asdfasdf/ 3
4 /ffffffff/ 2

===> 一对一

create table userinfo1(
id int auto_increment primary key,
name char(10),
gender char(10),
email varchar(64)
)engine=innodb default charset=utf8;

create table admin(
id int not null auto_increment primary key,
username varchar(64) not null,
password VARCHAR(64) not null,
user_id int not null,
unique uq_u1 (user_id),
CONSTRAINT fk_admin_u1 FOREIGN key (user_id) REFERENCES userinfo1(id)
)engine=innodb default charset=utf8;

c. 用户表（百合网） 相亲记录表

示例1：
用户表
相亲表

示例2：
用户表
主机表
用户主机关系表
===》多对多

create table userinfo2(
id int auto_increment primary key,
name char(10),
gender char(10),
email varchar(64)
)engine=innodb default charset=utf8;

create table host(
id int auto_increment primary key,
hostname char(64)
)engine=innodb default charset=utf8;

create table user2host(
id int auto_increment primary key,
userid int not null,
hostid int not null,
unique uq_user_host (userid,hostid),
CONSTRAINT fk_u2h_user FOREIGN key (userid) REFERENCES userinfo2(id),
CONSTRAINT fk_u2h_host FOREIGN key (hostid) REFERENCES host(id)
)engine=innodb default charset=utf8;


2. SQL语句数据行操作补充
create table tb12(
id int auto_increment primary key,
name varchar(32),
age int
)engine=innodb default charset=utf8;

增
insert into tb11(name,age) values('alex',12);

insert into tb11(name,age) values('alex',12),('root',18);

insert into tb12(name,age) select name,age from tb11;
删
delete from tb12;
delete from tb12 where id !=2
delete from tb12 where id =2
delete from tb12 where id > 2
delete from tb12 where id >=2
delete from tb12 where id >=2 or name='alex'

改
update tb12 set name='alex' where id>12 and name='xx'
update tb12 set name='alex',age=19 where id>12 and name='xx'
查

select * from tb12;

select id,name from tb12;

select id,name from tb12 where id > 10 or name ='xxx';

select id,name as cname from tb12 where id > 10 or name ='xxx';

select name,age,11 from tb12;

其他：
select * from tb12 where id != 1
select * from tb12 where id in (1,5,12);
select * from tb12 where id not in (1,5,12);
select * from tb12 where id in (select id from tb11)
select * from tb12 where id between 5 and 12;


通配符：

select * from tb12 where name like "a%"
select * from tb12 where name like "a_"


分页：

select * from tb12 limit 10;

select * from tb12 limit 0,10;
select * from tb12 limit 10,10;
select * from tb12 limit 20,10;

select * from tb12 limit 10 offset 20;
从第20行开始读取，读取10行；

结合Python分页：
# page = input('请输入要查看的页码')
# page = int(page)
# (page-1) * 10
# select * from tb12 limit 0,10; 1
# select * from tb12 limit 10,10;2


排序：
select * from tb12 order by id desc; 大到小
select * from tb12 order by id asc; 小到大
select * from tb12 order by age desc,id desc;

取后10条数据
select * from tb12 order by id desc limit 10;

分组：

select count(id),max(id),part_id from userinfo5 group by part_id;

count
max
min
sum
avg

**** 如果对于聚合函数结果进行二次筛选时？必须使用having ****
select count(id),part_id from userinfo5 group by part_id having count(id) > 1;

select count(id),part_id from userinfo5 where id > 0 group by part_id having count(id) > 1;


连表操作：

select * from userinfo5,department5

select * from userinfo5,department5 where userinfo5.part_id = department5.id

select * from userinfo5 left join department5 on userinfo5.part_id = department5.id
select * from department5 left join userinfo5 on userinfo5.part_id = department5.id
# userinfo5左边全部显示


# select * from userinfo5 right join department5 on userinfo5.part_id = department5.id
# department5右边全部显示



select * from userinfo5 innder join department5 on userinfo5.part_id = department5.id
将出现null时一行隐藏






select * from
department5
left join userinfo5 on userinfo5.part_id = department5.id
left join userinfo6 on userinfo5.part_id = department5.id


select
score.sid,
student.sid
from
score

left join student on score.student_id = student.sid

left join course on score.course_id = course.cid

left join class on student.class_id = class.cid

left join teacher on course.teacher_id=teacher.tid




select count(id) from userinfo5;



作业练习：
http://www.cnblogs.com/wupeiqi/articles/5729934.html
10-15个完成