18 . Go之操作Mysql

安装mysql

wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm
yum -y localinstall mysql57-community-release-el7-8.noarch.rpm
yum install mysql-community-server -y
systemctl start mysqld
grep 'temporary password' /var/log/mysqld.log
mysql -uroot -p
ALTER USER 'root'@'localhost' IDENTIFIED BY 'ZHOUjian.22';

grant all privileges on *.* to admin@"%" identified by 'ZHOUjian.21' withth grant option;

# 授权test用户有testdb数据库某一部分权限
grant select,update on testDB.* to test@'%' identified by 'ZHOUjian.22';

# 授权test用户拥有所有数据库所有权限
grant all on *.* to 'test'@'%' identified by 'ZHOUjian.22';
flush privileges;

Mysql常用库操作

# 创建数据库
mysql> create database myblog1 charset=utf8;

# 查询数据库
mysql> show databases;

# 查看数据库
mysql> show create database myblog;
+----------+-----------------------------------------------------------------+
| Database | Create Database                                                 |
+----------+-----------------------------------------------------------------+
| myblog   | CREATE DATABASE `myblog` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+-----------------------------------------------------------------+

# 删除数据库
mysql> drop database myblog1;

Mysql常用表操作

# 进入Myblog数据库
mysql> use myblog;

# 创建表
mysql> create table name (
    -> colname coltype 修饰,
    -> ) engine=inndb default charset=utf8mb4;

colname: 列名, 大小写英文字母,数字,_组成
coltype: 数值类型(int bigint float double decimal(m,n))
				 字符串类型(varchar(n), char(n))
			   时间类型(data,datetime,time)
				 文本类型(text 64k,mediumtext 16M,longtext 4G)
				 二进制类型(blob,longblob)
				 json/array()

# 修饰:
		# 主键: primary key
		# 唯一: unique
		# 自动增长: auto_increment
		# 默认值: default 0,default ''
		# 是否允许为Null, 不允许为NULL ,NOT NULL
		# 注释: COMMENT ''

# 索引
	index

创建表Example1

create table task(
id bigint primary key auto_increment,
name varchar(64) not null default '' comment '任务名称',
status int not null default 0 comment '状态,0: 新建, 1: 正在执行, 2: 停止, 3:  完成',
start_time datetime comment '开始时间',
complete_time datetime comment '完成时间',
deadline_time datetime not null comment '截止时间',
content text comment '任务详情',
index idx_name (name),
index deadline_time(deadline_time)
)engine=innodb default charset utf8mb4 auto_increment 1000;

# 查看表结构
mysql> desc task;

# 删除表
mysql> drop table name;

# 修改表
mysql> alter table name 动作;

# 只允许添加列
alter table name add column colname coltype 修饰;

# 删除列
alter table name drop column colname;

# 修改列
alter table name modify column colname coltype 修饰;

# 索引
create index name on table (column,column2,...);
drop index name on table (column,column2);
create unique index name on table (column,column2,...);

表数据操作

# 增 insert into table(c1,c2,c3,c4) values(v1,v2,v3,v4);
mysql> insert into task(name,content,deadline_time) values('写作业','完成todulist web', '2020-06-27 15:20:00');

# 删

# 改

# 查
mysql> select * from task;
+------+-----------+--------+------------+---------------+---------------------+--------------------+
| id   | name      | status | start_time | complete_time | deadline_time       | content            |
+------+-----------+--------+------------+---------------+---------------------+--------------------+
| 1000 | 写作业    |      0 | NULL       | NULL          | 2020-06-27 15:20:00 | 完成todulist web   |
+------+-----------+--------+------------+---------------+---------------------+--------------------+

# 指定列查询
mysql> select name,status,start_time from task;
+-----------+--------+------------+
| name      | status | start_time |
+-----------+--------+------------+
| 写作业    |      0 | NULL       |
+-----------+--------+------------+

# 条件查询
mysql> select name,status,start_time from task where name='写作业';
+-----------+--------+------------+
| name      | status | start_time |
+-----------+--------+------------+
| 写作业    |      0 | NULL       |
| 写作业    |      0 | NULL       |
+-----------+--------+------------+

# 逻辑关系
		与  and
		或	 or colname=v1 or colname = v2
		非	 not
				c1 = v1 and (c2 = v2 or c3 = v3)
		删	 delete from table;
				delete from table where 条件;

# 改
		update table
		set colname = v1, col2 = v2 ,col3 = v3;
		mysql> update task set status=1;

内置函数

# 获取当前时间
select now();

# 获取md5('1');
select md5('1')

# date_format(time,layout)

查询

insert into task(name,content,deadline_time) values('1','1','2020-05-20'),
('1','1','2020-05-21'),
('2','1','2020-05-22'),
('3','1','2020-05-23'),
('4','1','2020-05-24'),
('5','1','2020-05-25'),
('6','1','2020-05-26');
# 数量
count(*)
count(id)

mysql> select count(*) from task where status=1;

# as 别名

# 

# 排序
   order by colname [asc | desc],col2 [asc|desc]
mysql> select * from task order by deadline_time;

# 分页
# 展示多少条数据 每页的数据量
# 展示第几页 页面
# limit 限制查询数量
# offset 设置便宜
# 每页展示5条 limit 5
# 第一页offset 0
# 第二页offset 5
mysql> select * from task order by deadline_time limit 5 offset 0;

# 分组
# IP time url status_code
# ip 出现的次数
# status_code出现的次数
# url,status_code出现的次数
# ip url status_code出现次数
# group by
select [] from table group by colname,colname2 [having 过滤条件;]
#  select 元素必须是指定分组的列名或聚合类
mysql> select status,count(*) from task group by status;
+--------+----------+
| status | count(*) |
+--------+----------+
|      0 |        7 |
|      1 |        2 |
+--------+----------+

create table accesslog(
	id bigint primary key auto_increment,
  logtime datetime not null comment '访问时间',
  ip varchar(128) not null default '' comment '访问来源',
  url varchar(4096) not null default '' comment '访问地址',
  status int not null default 0 comment '状态码'
) engine=innodb default charset utf8mb4;

insert into accesslog(logtime,ip,url,status) values
('2020-06-05 05:20:00','1.1.1.1','/index',200),
('2020-06-06 05:20:00','1.1.1.2','/home',302),
('2020-06-07 05:20:00','1.1.1.3','/test.txt',404),
('2020-06-08 05:20:00','1.1.1.4','/backup.sh',404),
('2020-06-09 05:20:00','1.1.1.5','/login',200),
('2020-06-10 05:20:00','1.1.1.6','/register',200),
('2020-06-15 05:20:00','1.1.1.7','/test',200),
('2020-06-13 05:20:00','1.1.1.8','/upload.php',200),
('2020-06-15 05:20:00','1.1.1.9','/index',200);

# ip出现次数
mysql> select ip,count(*) from accesslog group by ip;
+---------+----------+
| ip      | count(*) |
+---------+----------+
| 1.1.1.1 |        1 |
| 1.1.1.2 |        1 |
| 1.1.1.3 |        1 |
| 1.1.1.4 |        1 |
| 1.1.1.5 |        1 |
| 1.1.1.6 |        1 |
| 1.1.1.7 |        1 |
| 1.1.1.8 |        1 |
| 1.1.1.9 |        1 |
+---------+----------+

# status_code出现次数
mysql> select status,count(*) from accesslog group by status;
+--------+----------+
| status | count(*) |
+--------+----------+
|    200 |        6 |
|    302 |        1 |
|    404 |        2 |
+--------+----------+

# ip url status_code出现次数
mysql> select url,status,count(*) from accesslog group by url,status;
+-------------+--------+----------+
| url         | status | count(*) |
+-------------+--------+----------+
| /backup.sh  |    404 |        1 |
| /home       |    302 |        1 |
| /index      |    200 |        2 |
| /login      |    200 |        1 |
| /register   |    200 |        1 |
| /test       |    200 |        1 |
| /test.txt   |    404 |        1 |
| /upload.php |    200 |        1 |
+-------------+--------+----------+

# ip访问次数大于等于1
mysql> select ip,count(*) from accesslog group by ip having count(*)>=1;
+---------+----------+
| ip      | count(*) |
+---------+----------+
| 1.1.1.1 |        1 |
| 1.1.1.2 |        1 |
| 1.1.1.3 |        1 |
| 1.1.1.4 |        1 |
| 1.1.1.5 |        1 |
| 1.1.1.6 |        1 |
| 1.1.1.7 |        1 |
| 1.1.1.8 |        1 |
| 1.1.1.9 |        1 |
+---------+----------+

# 每一天的访问量
mysql> select date_format(logtime,'%Y-%m-%d') as log_day,count(*) as cnt from accesslog group by log_day;
+------------+-----+
| log_day    | cnt |
+------------+-----+
| 2020-06-05 |  18 |
+------------+-----+

mysql> select date_format(logtime,'%Y-%m-%d') as log_day,count(*) as cnt from accesslog group  by log_day order by cnt desc;

create table score(
	id bigint primary key auto_increment,
  day date not null comment '日期',
  name varchar(32) not null default '' comment '姓名',
  score float not null default 0 comment '分数'
)engine=innodb default charset utf8mb4;

insert into score(day,name,score) values
('2020-05-20','youmen',2),
('2020-05-21','xiaobai',3),
('2020-05-22','haba',4),
('2020-05-23','wunai',5),
('2020-05-24','Amaris',6),
('2020-05-25','Cassiel',6),
('2020-05-26','Gina',6),
('2020-05-27','Deirdre',6);

# 求和
mysql> select name,sum(score) from score group by name;
+---------+------------+
| name    | sum(score) |
+---------+------------+
| Amaris  |          6 |
| Cassiel |          6 |
| Deirdre |          6 |
| Gina    |          6 |
| haba    |          4 |
| wunai   |          5 |
| xiaobai |          3 |
| youmen  |          2 |
+---------+------------+

# 最小值,最大值,平均值
mysql> select name,sum(score),max(score),min(score),avg(score) from score group by name;
+---------+------------+------------+------------+------------+
| name    | sum(score) | max(score) | min(score) | avg(score) |
+---------+------------+------------+------------+------------+
| Amaris  |          6 |          6 |          6 |          6 |
| Cassiel |          6 |          6 |          6 |          6 |
| Deirdre |          6 |          6 |          6 |          6 |
| Gina    |          6 |          6 |          6 |          6 |
| haba    |          4 |          4 |          4 |          4 |
| wunai   |          5 |          5 |          5 |          5 |
| xiaobai |          3 |          3 |          3 |          3 |
| youmen  |          2 |          2 |          2 |          2 |
+---------+------------+------------+------------+------------+

# 每一天的总分

# 联查

# 多张表进行查询数据
join
left join on
inner join on
right join on

create table user(
		id bigint primary key auto_increment,
  	name varchar(32) not null default '',
  	status int not null default 0 comment '0:在职,1:离职'
)engine=innodb default charset utf8mb4;

alter table task add column user bigint;

insert into user(name,status) values
('youmen',0),
('幽梦',1),
('wunai',0);

insert into task(name,content,deadline_time,user) values
('完成web任务','',now(),1),
('打游戏','',now(),0),
('吃饭','',now(),1),
('睡觉','',now(),2);

# 每个人(名字)未完成的任务

配置数据库驱动

数据库编程属于beego中的Models层,也称为ORM模块

在beego中,目前支持三种数据库驱动,分别是:

// MySQL： github.com/go-sql-driver/mysql
// PostgreSQL：github.com/lib/pq
// Sqlite3：github.com/mattn/go-sqlite3

go get  github.com/go-sql-driver/mysql

beego中的ORM所具备的几个特性

// 1. 支持G语言的所有类型存储
// 2. CRUD操作简单
// 3. 自动Join关联表
// 4. 允许直接使用SQL查询