mysql客户端命令
管理：
help ? \h : 查看帮助，查看mysql的管理命令
\G:格式化查询，结果以key:value形式展示
\c:结束当前的sql语句
status \s:查看mysql状态信息
source \.：导入sql文件
use \u：切换数据库
mysqladmin客户端管理命令
#查看MySQL进程是否存活
[root@db01 ~]# mysqladmin ping
mysqld is alive
#查看mysql信息
[root@db01 ~]# mysqladmin status
#关闭mysql进程
[root@db01 ~]# mysqladmin shutdown
#查看MySQL当前参数
[root@db01 ~]# mysqladmin variables
#库外创建数据库
[root@db01 ~]# mysqladmin create aaa
#库外删除数据库
[root@db01 ~]# mysqladmin drop aaa
#刷新binlog日志
[root@db01 ~]# mysqladmin flush-log
#修改密码
[root@db01 ~]# mysqladmin password '123'
SQL语句
DDL 数据定义语言
开发规范：库名，表名 小写
1.库
create（创建）
Syntax:
CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
[create_specification] ...
create_specification:
[DEFAULT] CHARACTER SET [=] charset_name
| [DEFAULT] COLLATE [=] collation_name
create_specification:
#避免库已存在 报错
mysql> create database if not exists zls;
#规范创建数据库
mysql> create database if not exists test1 default character set utf8 default collate utf8_general_ci;
mysql> create database if not exists test1 charset utf8 collate utf8_general_ci;
drop（删除）
mysql> drop database zls;
alter（修改）
mysql> show create database zls1;
+----------+---------------------------------------------------------------+
| Database | Create Database |
+----------+---------------------------------------------------------------+
| zls1 | CREATE DATABASE `zls1` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+---------------------------------------------------------------+
1 row in set (0.00 sec)
#修改字符集
mysql> alter database zls1 charset gbk;
Query OK, 1 row affected (0.00 sec)
mysql> show create database zls1;
+----------+--------------------------------------------------------------+
| Database | Create Database |
+----------+--------------------------------------------------------------+
| zls1 | CREATE DATABASE `zls1` /*!40100 DEFAULT CHARACTER SET gbk */ |
+----------+--------------------------------------------------------------+
#修改校验规则
mysql> alter database test1 collate utf8_bin;
2.表
创建表create
create table tlbb(
aid int,
name varchar(12),
gender enum('nan','nv'),
age tinyint,
phone int);
数据类型
int： 整数 -2^31 ~ 2^31 -1
varchar：字符类型 （变长）
char： 字符类型 （定长）
tinyint： 最小整数 -128 ~ 128
enum： 枚举类型
datetime： 时间类型 年月日时分秒
学生表：student
sid sname sage sgender cometime
create table student2(
sid int not null primary key auto_increment comment '学号',
sname varchar(10) not null comment '学生姓名',
sage tinyint unsigned comment '学生年龄',
sgender enum('m','f') not null default 'm' comment '学生性别',
cometime datetime not null default NOW() comment '入学时间');
约束：
not null：非空
--------------------------------------------------------------------------------
primary key：主键（唯一，且非空）
unique key：唯一键（可以为空）
pk = uk + not null
--------------------------------------------------------------------------------
auto_increment：自增
unsigned：无符号，和数字结合用，就是非负数
default：默认值
unique key
comment：注释
删除表drop
mysql> drop table student;
修改表
#修改表名
mysql> alter table tlbb rename student;
#增加字段
mysql> alter table stu add gsb varchar(10);
#将字段插入到最前面
mysql> alter table stu add youfeng int first;
#将字段插入到某个字段的后面
mysql> alter table stu add xmg int after ljk;
#删除某个字段
mysql> alter table stu drop ljk;
#修改字段的属性
mysql> alter table stu modify qls char(10);
#修改字段名和属性
mysql> alter table stu change qls haoda int;
DCL数据控制语言
grant
grant all on *.* to root@'%' identified by '1';
grant all privileges on *.* to pri2@'%' identified by '1';
grant all on *.* to root@'%' identified by '1' with max_user_connections 1;
revoke
mysql> revoke select on *.* from pri1@'%';
DML 数据操作语言
增：insert
#注意：所有值必须一一对应，如果没有就给null
mysql> insert into student2 values(null,'qls',18,'m',now());
#注意：只需要给前面的key添加value，前面key值的顺序可以随意，后面value必须对应
mysql> insert into student2(sname,sage,sgender) values('zls',18,'m');
mysql> insert into student2(sage,sname,sgender) values(18,'zls','m');
#插入多条数据
mysql> insert into student2(sname,sage,sgender) values('zls',18,'m'),('qls',18,'f');
改：update
mysql> update student2 set sgender='f';
#规范用法 必须接where条件
mysql> update student2 set sgender='f' where sid=1;
mysql> update student2 set sage=20 where 1=1;
删：delete
# 必须接条件
mysql> delete from student2 where sid=2;
mysql> delete from student2 where sid>3 and sid<9;
使用update代替delete做伪删除
1.添加一个状态列
mysql> alter table student2 add state enum('1','0') default '1';
2.使用update删除
mysql> update student2 set state='0' where sid=9;
3.查询的时候接条件
mysql> select * from student2 where state=1;
DQL数据查询语言
select 基础用法
#查询city表中的所有内容
mysql> select * from city;
#查询指定列的内容
mysql> select name,countrycode from city;
#指定条件查询
mysql> select * from city where name='afuhan';
#limit（翻页功能）
mysql> select * from city limit 10;
mysql> select * from city limit 10,10;
#多条件查询> 、< 、>=、<=、<>(!=)
mysql> select * from city where countrycode='chn' and population>999999;
#模糊查询
mysql> select * from city where countrycode like 'H%';
mysql> select * from city where countrycode like '%H';
mysql> select * from city where countrycode like '%H%';
#排序（顺序）
mysql> select id,name,population,countrycode from city order by population limit 0,60;
#排序（倒叙）
mysql> select id,name,population,countrycode from city order by population desc limit 0,60;
#group by + 聚合函数
#聚合函数种类：
#max()
#min()
#avg()
#sum()
#count()
#distinct()
#password()
#now()
#database()
+------------+
| database() |
+------------+
| world |
+------------+
#此时此刻，我想吟诗一首
1.遇到统计想函数
2.形容词前group by
3.函数中央是名词
4.列名select后添加
#统计世界上每个国家的总人口数
select countrycode,sum(population) from city group by countrycode;
#统计中国各个省的人口数量(练习)
不加别名：
mysql> select District,sum(population) from city where countrycode='CHN' group by District order by sum(population);
别名：
mysql> select District as 省,sum(population) as 人口 from city where countrycode='CHN' group by 省 order by 人口;
#统每个国家的城市数量(练习)
select countrycode,count(name) from city group by countrycode order by count(name);
mysql> select countrycode,count(name) from city where countrycode='chn' group by countrycode order by count(name);
#and
mysql> select * from city where countrycode='CHN' and id>500;
#or
mysql> select * from city where countrycode='CHN' or countrycode='USA';
#in
mysql> select * from city where countrycode in ('CHN','USA');
####### 联合查询 效率比in和or高
mysql> select * from city where countrycode='CHN' union all select * from city where countrycode='USA';
select 高级用法
1.多表联查（传统连接）
集合：
A: 1 2 3
B: 2 3 4
交集：23
并集：1234
差集：14
id：1 2 3
name: qls haoda zhang3
id： 1 2 3
mark：80 90 120
+-------+-----+
|name | mark|
+-------+-----+
|haoda | 90 |
+-------+-----+
mysql> create table st(id int ,name varchar(10));
Query OK, 0 rows affected (0.02 sec)
mysql> create table score(id int ,mark int);
Query OK, 0 rows affected (0.01 sec)
mysql> insert st values(1,'qls'),(2,'haoda'),(3,'zhang3');
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> insert score values(1,80),(2,90),(3,120);
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0
#查世界上人口数量小于100的城市在哪个国家，城市和国家人口数量分别是多少？
城市名 国家名 城市人口数量 国家人口数量
city.name country.name city.population country.population
select city.name,country.name,city.population,country.population
from city,country
where city.countrycode=country.code
and city.population<100;
#世界上人口数量小于100的城市在哪个国家，说的什么语言？
select city.population,city.name,country.name,countrylanguage.language
from city,country,countrylanguage
where city.countrycode=country.code and countrylanguage.countrycode=country.code
and city.population < 100;
mysql> select * from world.city limit 1\G
ID: 1
Name: Kabul
CountryCode: AFG
District: Kabol
Population: 1780000
mysql> select * from world.country limit 1\G
Code: ABW
Name: Aruba
Continent: North America
Region: Caribbean
SurfaceArea: 193.00
IndepYear: NULL
Population: 103000
LifeExpectancy: 78.4
GNP: 828.00
GNPOld: 793.00
LocalName: Aruba
GovernmentForm: Nonmetropolitan Territory of The Netherlands
HeadOfState: Beatrix
Capital: 129
Code2: AW
mysql> select * from world.countrylanguage limit 1\G
CountryCode: ABW
Language: Dutch
IsOfficial: T
Percentage: 5.3
2.内连接 join on(企业常用)
#查世界上人口数量小于100的城市在哪个国家，城市和国家人口数量分别是多少？
select city.name,city.population,country.name,country.population
from city,country
where city.countrycode=country.code
and city.population<100;
select city.name,city.population,country.name,country.population
from city join country
on city.countrycode=country.code
where city.population<100;
#世界上人口数量小于100的城市在哪个国家，说的什么语言？
·A join B on 1 join C on 2 join D on 3·
select city.population,city.name,country.name,countrylanguage.language
from city,country,countrylanguage
where city.countrycode=country.code and countrylanguage.countrycode=country.code
and city.population < 100;
select city.population,city.name,country.name,countrylanguage.language
from city
join country
on city.countrycode=country.code
join countrylanguage
on countrylanguage.countrycode=country.code
where city.population < 100;
建议：小表在前大表在后
3.自连接 natural join
# 人口数量大于1000000的城市所在的国家，他们都说什么语言？
city.population,city.name,city.countrycode,countrylanguage.language
select city.population,city.name,city.countrycode,countrylanguage.language
from city,countrylanguage
where city.countrycode=countrylanguage.countrycode
and city.population > 1000000;
# 人口数量大于1000000的城市所在的国家，他们都说什么语言？ (自连接)
select city.population,city.name,city.countrycode,countrylanguage.language
from city natural join countrylanguage
where city.population > 1000000;
前提条件：一定要有相同的列名字，并且列中的数据一致
4.外连接（左外连接，右外连接）
#左外连接
mysql> select city.name as 城市名称,country.code as 国家代码,country.name as 国家名称 from city left join country on city.countrycodde=country.code and city.population<100 limit 10;
#右外连接
mysql> select city.name as 城市名称,country.code as 国家代码,country.name as 国家名称 from city right join country on city.countrycodde=country.code and city.population<100 limit 10;
字符集
字符集：是一个系统支持的所有抽象字符的集合。字符是各种文字和符号的总称，包括各国家文字、标点符号、图形符号、数字等。
字符集设置
系统层：
#C6:
vim /etc/sysconfig/i18n
LANG="en US.UTF-8 "
#C7:
[root@db01 ~]# vim /etc/locale.conf
LANG="en_US.UTF-8"
工具 xshell:
MySQL：
#永久
#修改配置文件/etc/my.cnf
[mysqld]
character-set-server=utf8
#临时
mysql> set character_set_server=utf8;
从规范保证字符集
#建库
create database db_name charset utf8 collate utf8_xxx_ci;
#建表
create table tb_name(id int) charset utf8 collate utf8_xxx_ci;
gbk 500-60000
utf8 1-90000
gb2312 2-5000
修改数据库的字符集
mysql> alter database zls charset utf8;
修改表的字符集
mysql> alter table zls charset gbk;
企业中修改某个库中的所有表字符集：
# mysqldump -uroot -p123 -B xx > /tmp/xx.sql
# vim /tmp/xx.sql
# :%s#gbk#utf8#g
# mysql -uroot -p123 < /tmp/xx.sql
update t_char set moneyyb=9999999 where aid=150;
